The Obama campaign is quickly striking back at the RNC's spot on energy policy, airing an ad of their own that goes after John McCain.

The ad will run in the same four swing states as the RNC's spot -- Michigan, Ohio, Pennsylvania and Wisconsin -- and rebuts the GOP's accusation that Obama doesn't have an energy plan in two ways: Explaining what Obama's policies actually are, and tying John McCain to the unpopular President Bush.

Check it out:

"McCain and Bush support a drilling plan that won't produce a drop of oil for seven years," the announcer says. "McCain will give more tax breaks to big oil. He's voted with Bush 95% of the time."

Looks like the Republican money machine is really gearing up to go after Barack Obama.

The Republican National Committee -- the one arm of the GOP that has consistently out-raised its Democratic counterpart -- is planning to throw its formidable cash advantage into a new round of ads going after Barack Obama, set to air in the swing states of Michigan, Ohio, Pennsylvania and Wisconsin.

Roll Call reports that the RNC's initial ad campaign will cost $3 million, and go after Obama on "energy security" -- clearly part of McCain's current efforts to rephrase the issue of fuel prices in terms of national security rather than economics. The RNC's ad campaign was first reported by the Politico.

Despite all the talk about Barack Obama's fundraising prowess, it's worth keeping it in some perspective. The most recent numbers up through May showed that the RNC had a $50 million advantage over the DNC, way ahead of Obama's cash lead over McCain -- thus giving the GOP the real advantage in this area for now, unless the June numbers and Obama's decision to opt out of public finance can change things drastically.

A new Rasmussen poll of Pennsylvania gives Barack Obama a narrow lead over John McCain in this must-win state. The numbers: Obama 46%, McCain 42%, with a ±3% margin of error.

And despite the constant message in the primaries that Obama wouldn't be able to win "beer track" voters, the pollster's analysis has this: "Obama has a sizable lead among those voters earning less than $40,000 a year, with McCain well ahead among those who earn more than that annually."

Even if we factor out African-American voters who are more economically downscale, this would still suggest Obama is doing solidly among white blue-collar voters.

New polling from Quinnipiac has some very bad news for John McCain, with him trailing in all three of the largest swing states -- even Florida:

Florida
Obama (D) 47%, McCain (R) 43%
Margin of error: ±2.6%

Ohio
Obama (D) 48%, McCain (R) 42%
Margin of error: ±2.6%

Pennsylvania
Obama (D) 52%, McCain (R) 40%
Margin of error: ±2.5%

According to our Election Central Poll Tracker, this is the first poll ever in which Obama has led McCain in Florida. Obama previously had a lot of trouble here thanks to the primary controversies that kept him out of the state, but this poll shows he's overcoming that difficulty rather quickly. Even if part of it is a post-primary boost, it would still seem to say that any ill will from the primaries is over with.

At a fundraiser last night in Philadelphia -- a unity event of sorts, featuring former Hillary-backers Ed Rendell and Michael Nutter -- Barack Obama vowed that he will not be passive in the face of political attacks: "If they bring a knife to the fight, we bring a gun."

Obama has to strike a careful balance between his promises of hope and optimism, against the pitfall of allowing himself to become a political doormat. One benefit of the long primary season is that he learned how to pull that trick off against Hillary Clinton -- and now he can do it against John McCain.

The McCain camp was quick to object: "Barack Obama's call for 'new politics' is officially over."

Barack Obama will be attacking John McCain today on Social Security -- a crucial political issue that could help him get a better share among middle-aged voters and senior citizens, if he can successfully tie McCain to President Bush's failed 2005 push to privatize Social Security.

"He said he supports private accounts for Social Security - in his words, 'along the lines that President Bush proposed,'" Obama will say in Philadelphia, according to pre-released excerpts. "Yesterday he tried to deny that he ever took that position, leaving us wondering if he had a change of heart or a change of politics."

A new set of polls from Quinnipiac gives some credibility to the Clinton campaign's argument that Hillary is the more electable Democrat. She does better than Obama against McCain in the big three swing states, and he's currently running behind in two out of the three:

Florida
McCain (R) 45%, Obama (D) 41%
Clinton (D) 48%, McCain (R) 41%

Ohio
McCain (R) 44%, Obama (D) 40%
Clinton (D) 48%, McCain (R) 41%

Pennsylvania
Obama (D) 46%, McCain (R) 40%
Clinton (D) 50%, McCain (R) 37%

It's unlikely that these numbers alone would be enough to get super-delegates to overturn the pledged-delegate majority for Obama, but it does lend weight to Hillary's electability argument.

A new batch of polls from Quinnipiac University lends weight to Hillary Clinton's argument that she's more electable against McCain than Obama -- it finds that she handily beats McCain in Florida, Ohio and Pennsylvania, while Obama only wins in one of the three:

Florida
Clinton (D) 49%, McCain (R) 41%
McCain (R) 44%, Obama (D) 43%

Sample: 1,411 Florida voters. Margin of error: ±2.6%.

Ohio
Clinton (D) 48%, McCain (R) 38%
McCain (R) 43%, Obama (D) 42%

Sample: 1,127 Ohio voters. Margin of error: ±2.9%.

Pennsylvania
Clinton (D) 51%, McCain (R) 37%
Obama (D) 47%, McCain (R) 38%

Sample: 1,494 Florida voters. Margin of error: ±2.5%.

On the bright side for Obama, his showings in Florida and Pennsylvania have improved since the last poll from a month ago. However, Hillary is still outperforming him in all three states.

Today's Gallup tracking poll shows that Hillary Clinton is definitely enjoying a bounce in the wake of her Pennsylvania primary win. The numbers, compared to yesterday:

Obama 48% (-1)
Clinton 47% (+3)

From Gallup's analysis:

The latest results, based on Gallup Poll Daily tracking from April 22-24, include two days of interviews conducted entirely after Tuesday's Pennsylvania Democratic primary. Support for Clinton is significantly higher in these post-primary interviews than it was just prior to her Pennsylvania victory, clearly suggesting that Clinton's win there is the catalyst for her increased national support.

A new Rasmussen poll of Pennsylvania shows Hillary Clinton running stronger than Barack Obama against John McCain here -- the sort of number likely to be touted by the Clinton campaign to demonstrate superior electability:

McCain (R) 44%, Obama (D) 43%
Clinton (D) 47%, McCain (R) 42%

While Obama is able to outperform Clinton among independent voters, Clinton is doing a better job at holding down the core Democratic base -- meaning that some of those Pennsylvania Dems who don't like Obama are at least seriously considering going for McCain.

Other polls have shown a similar situation: The current Pollster.com averages have Clinton beating McCain in Pennsylvania by 45.7%-43.2%, but McCain beating Obama by 45.2%-42.7%.

Hillary Clinton might have just reached Terry McAuliffe's prediction of raising $10 million since the polls closed in Pennsylvania. The Washington Post reports that the campaign has taken in more than $10 million, according to campaign aides -- a sum that was badly needed in light of her recent money problems.

On the other hand, the New York Times puts the number at only $8 million, though it's not clearly sourced. It's possible that the number was $8 million when the Times reporters found out, and then rose to $10 million afterward, or that different staffers have heard different numbers themselves.

Another thing that's unclear is how much of this money will be available for the primary. What is nearly certain, however, is that Barack Obama will still have more overall cash, as he went into this month with over $40 million on hand and barely any debts.

Late Update: The Times has updated their numbers, confirming that Clinton did in fact succeed in raising $10 million.

Here's are MSNBC's most recent numbers tallying up the breakdown of Pennsylvania's 158 delegates:

Hillary 75

Obama 65

Not allocated yet 18

According to MSNBC's political team, Obama now leads by 156 pledged delegates: 1,482-1,326.

And the current superdelegate total is Clinton 262, Obama 237.

That means that Obama now leads by 131 delegates overall: 1,719-1,588.

Other networks have different counts. Total required to win: 2,025.

Meanwhile, here's the Associated Press' popular vote breakdown of yesterday's vote, with 99% reporting:

Hillary 1,258,245

Obama 1,042,296

Our handy Election Central calculator tells us that gives Hillary a net popular-vote gain of 215,949.

So emails Hillary spokesperson Phil Singer:

As of 11:30PM tonight, we are at nearly $2.5 million since PA was called for HRC -- 80% of that money is coming from new donors to the campaign. It's our best night ever.

MSNBC, Fox, ABC and CBS call it for Hillary.

With three percent reporting, it's 53%-47%.

Late Update: Clinton spokesperson Mo Elleithee gives us the instant spin from the Hillary camp about the impact tonight's victory will have on the super-delegates:

"There's beginning to be a subtle shift of psychology of a lot of the uncommitted supers," Elleithee said. "[They] are beginning to wonder why Obama has been unable to win this thing despite all the advantages he has."

"There's a lot of questions that are beginning to surface about him," he said, while superdelegates are learning that "every time she's got her back up against the wall, she delivers."

There were reports today that a bloc of supers were preparing to break to Obama. It will be interesting to see if that materializes -- and also interesting to see if Hillary's Pennsylvania win translates into a greater corralling of super-del support than she's been able to pull off thus far.

Late Update: Hillary top adviser Terry McAuliffe spins Hillary's victory, arguing that the pledged del count shouldn't necessarily decide who the Dem primary winner was.

McAuliffe also brazenly predicts that Hillary will win the popular vote in the end -- Florida included, of course.

Late Update: New exit poll numbers from tonight show that whoever wins the nomination, many Dems in Pennsylvania are at risk of defecting to McCain.

Late Update: The latest numbers: With 57% reporting, Hillary leads by 10 points, 55%-45%. Of course, as Chuck Todd just said on MSNBC, some precincts likely to heavily favor Obama have yet to be counted. So we'll see.

Late Update: In her victory speech, Hillary primes her supporters for the tough road ahead.

Late Update: Obama kicks off his concession speech, and graciously concedes that Hillary "ran a terrific race."

Late Update: With nearly 80% reporting, Hillary leads by 10 points, 55%-45%.

Obama spokesperson Bill Burton argues, via instant messaging, that the exit polls show already that in Pennsylvania Obama is doing better among key groups than he did in Ohio, a state with similar demographic advantages for Hillary:

Significant improvements over Ohio, especially among white men and seniors overall.

With voters over 60 in OH, Clinton won 69%, Obama got 28%. In PA, Obama earned 41% of the vote among voters over 60, and Clinton won 59%. The gap among seniors was cut by more than half, from 41 to 19.

Among white men, in Ohio, Obama got 39%, in PA, 46%. Clinton was at 58% in OH and dropped to 53% in PA. The gap narrowed from 19% to 7%.

It's worth keeping in mind that for various reasons Pennsylvania is actually more demographically advantageous to Hillary than Ohio was -- a fact that could either redound to her benefit or to her disadvantage, depending on what happens tonight.

MSNBC reports that Obama has already outspent Hillary two-to-one on TV ad time in Indiana and North Carolina.

This, combined with Obama's massive cash-on-hand advantage -- he has over $40 million, she's in the red -- make it that much tougher for her to make a credible case for staying in the race without a very decisive victory tonight.

The Hillary campaign, relying on figures supplied by its media buyer, sends out these startling facts about Obama's ad spending in Pennsylvania:

In PA, Sen. Obama spent a total of $11,246,573 on media, which is the most he has spent in any state to date...

The average viewer in PA would have been exposed to more than 100 viewings of an Obama spot.

Sen. Obama's spots ran almost 10,000 times on TV [estimated 9550]

If the Obama campaign contests these figures, I'll let you know.

Meanwhile, the question is this: Did the Hillary campaign send these stats out to minimize the damage of what they're expecting to be a smaller-than-projected win? Or did they send them out to maximize the impact of what they project will be a sizable victory?

We'll find out soon enough.

There's been a bit of confusion out there about supposed "ballots" that have been popping up in Pennsylvania today bearing the name of only one candidate.

Some alarmed readers have written in about them, suggesting voting irregularities. Others have made similar points in the blogosphere.

But these aren't irregularities at all, it turns out.

First, the visuals. Here's one that was sent to us by the Clinton campaign that only has Obama's name on it (click to enlarge)...

...and here's one, courtesy of Wonkette, with only Hillary's name on it (click to enlarge)...

Philly-resident Atrios has an explanation of what this is all about. These are not actual ballots. Rather, they are "sample ballots," handed out by a given candidate's supporters, basically telling voters who to vote for and how to vote for him or her.

To be clear, the Hillary campaign is not alleging irregularities around this. The Hillary camp sent over the Obama-only sample ballot only to clarify that this is happening on both sides and that it isn't irregular. The Obama campaign is not alleging irregularities around the Hillary-only sample ballot, either.

You're supposed to use that teeth-grindingly awful cliche on days like today, so I thought I'd give you a whole post with that name.

So here, in no particular order, is today's reading list on expectations for tonight, the setting of expectations for tonight, the spinning of expectations in advance of tonight, and all things expectation-related...

* The Obama campaign puts out a memo saying that Hillary needs a huge win tonight but adds that even a huge win wouldn't make any difference in the long run, anyway.

* Mark Blumenthal says that the polling showing a Hillary win is inconclusive, and rather aptly describes the polls as "blunt instruments."

* Adam Nagourney says that if the Hillary camp wins by less than 10 points and tries to spin it as a victory, things will "get murky."

* Jake Tapper quite rightly wonders why it is that we've all decided that frontrunner Barack Obama, who's outspending Hillary by three-to-one, isn't supposed to win in a big state like Pennsylvania.

* Hillary wonders, or pretends to wonder, why it is that Obama can't "close the deal' with voters.

* Atrios, after remaining scrupulously neutral for this whole primary and heaping much disdain on the whole process itself -- and on the two candidates from time to time -- votes today for Obama, increasing the chance of an Obama victory by one vote.

* And finally, because you all forgot this, I reported a few weeks ago that Obama privately told a group of California donors that a Hillary win of less than 10 points would be a "victory" for him.

The final InsiderAdvantage poll of the Pennsylvania primary gives Hillary Clinton a good-sized lead here, but with some possible last-minute momentum for Barack Obama. The numbers, compared to yesterday:

Clinton 49% (+0)
Obama 42% (+3)

From the internals: Clinton leads 53%-38% among women, while Obama leads 48%-45% among men.

The polls close in six-and-a-half hours.

Today is the big day: The Pennsylvania primary. Heavy turnout is expected for a race in which the candidates have been pummeling each other for six weeks, and long lines have already formed at voting stations.

Hillary Clinton is expected to win the primary, with the margin being the big question. If Barack Obama is able to keep it close, then Clinton will be unable to make much of a dent in either his delegate and popular vote leads.

The polls close at 8 p.m., with results set to come in soon afterwards. We'll be live-blogging the results here at TPM.

Zogby's final tracking poll numbers in Pennsylvania find Hillary expanding her lead to beyond the margin of error:

Hillary 51% (yesterday 48%)

Obama 41% (yesterday 42%)

The poll finds Hillary edging over 50% and into a double-digit lead. She's up five points from two days ago and six from five days ago. The latest expansion of three points is larger than other recent gains, suggesting the possibility (if Zogby is right) that the late-breakers are turning her way.

Still, six percent remain undecided. So Obama could still make the outcome much closer than the decisive victory she needs, something that would significantly ratchet up pressure on her to drop out of the race.

I've just obtained audio of a harsh new robocall the Hillary campaign is pumping into Pennsylvania -- it directly accuses Obama twice of lying about his position on the Second Amendment, and says explicitly that it's an issue that John McCain will use against him in November.

Give it a listen...

Here's the transcript:

Hello, this is Hillary Clinton for president calling. Barack Obama is not telling the truth about his past position on the Second Amendment.

As an Illinois state Senator, he supported a ban on all handguns, and he even personally filled out a questionnaire saying he supported the ban. Now instead of telling you the truth about that, he's trying to cover it up, saying he never saw the questionnaire -- even though his handwriting was on it.

And Obama voted to give millions of dollars to anti-gun organizations that are trying to take away our gun rights.

This is just another example of Barack Obama saying one thing, and doing another -- and yet another issue John McCain will use against Obama to win in November.

A piece on Obama's handwriting being on the gun questionnaire is here, and one on the anti-gun group Obama voted to financially support is here.

The Hillary campaign confirmed that the call was theirs, but I was unable to determine where in Pennsylvania the call is being made.

The assertion that McCain could use this against Obama in November dovetails with the larger "values" and "electability" argument the Hillary campaign has been making in the wake of Obama's "small town" comments -- that his positions on guns and other matters render him incapable of winning over the blue collar whites that defected from John Kerry in 2004. This robocall adds the extra charge that Obama has been falsifying his positions on the core gun questions.