Barack Obama has just given a lengthy interview to PBS' Gwen Ifill about his views on Iraq, and according to advance excerpts, he elaborated on his desire to hear input from the commanders on how to withdraw responsibly.

Obama's suggestion that he wants to confer with commanders over withdrawal has been spun by John McCain and the GOP -- with the complicity of some in the national media -- as proof that he's softened on having a withdrawal timetable.

But in the interview, Obama goes into a bit more detail than I've seen before about what he wants to discuss with the commanders -- in particular, how to handle the logistics of leaving a residual force behind. Asked what he means by "residual force," Obama said...

SEN. OBAMA: Well, this is one of the things I want to discuss when I travel there. And I think that it's important to have the commanders on the ground help to shape what is going to be necessary for limited missions that have been defined by the president, the commander in chief.

The missions that I've called for: as you said, protecting diplomatic forces and civilians, U.S. civilians or foreign civilians in Iraq, making sure that we are protecting our bases, training Iraqi forces, if, as long as we are [sure] of the fact that we are not training them to engage in sectarian war but rather training them for the integrated force structures that are needed to protect them, and to have a counterinsurgency force that can act swiftly if you start seeing the reemergence of al Qaeda in Iraq.

Those would be the limited missions that they would be carrying out. I think we need to make sure that the commanders have the resources they need in order to be able to deal with those issues.

The interview will air tonight at 7:00 E.T. More excerpts after the jump.

MS. IFILL: Today we hear that General Motors is restructuring; Fannie and Freddie Mae are the subjects of a rescue attempt by the government; inflation worries are up again. Would you do what this president has done, if you were president, to try to set this economy right?

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SEN. OBAMA: I think it is important, with respect to Freddie Mac and Fannie Mae, that we ensure there's continued liquidity in the housing market, but that we're not devoting huge sums of money to bailing out shareholders or CEOs. I mean, I think that there's got to be some recognition that you can't have those institutions with all upside but no downside, at least for the investors. But we do have to make sure that we have a stable housing market. That, I think, will help a lot in the short term.

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MS. IFILL: I would like to talk to you about Iraq. You gave a big speech on that subject today. A new poll out shows Americans are kind of split about whether there should be a withdrawal timetable or not. So is John McCain right or are you?

SEN. OBAMA: Well, you won't be surprised to learn that I'm right. (Chuckles.)

MS. IFILL: Oh, I'm surprised.

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SEN. OBAMA: My opposition to the war in Iraq from the start was never premised on the day-to-day tactics that we employ once we are in Iraq. I've never had any doubt that the U.S. military would defeat Saddam Hussein's army. There was never any doubt that if we poured enough resources in there, that we could lock down Iraq. The problem has always been a broader strategic question, and that is was it wise for us to go in there in the first place and once we were in there, you know, was it wise for us to continue a long-term occupation in Iraq. That remains the question.

So John McCain wants to argue about tactics; you know, have we seen a reduction in violence in Iraq. Absolutely, and that's a testament to the extraordinary work of our U.S. military. Can we sustain spending $10 billion a month, putting enormous strains on military families, at a time when the central front on terror -- Afghanistan and the hills in northwest Pakistan -- are deteriorating, and we are seeing brazen attacks against U.S. military bases in the region by al Qaeda operatives? And what I have said continuously is that in light of the problems that we're having in Afghanistan, in light of other security threats that we have out there, non-proliferation issues, Iran, what we're doing with respect to China, what we're doing with respect to North Korea, it is important for us not to be single-minded about Iraq. And it is time for us to begin a phase-three deployment and have a timetable attached to that, something that the American people and the Iraqi government have said that they are prepared to see.

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MS. IFILL: Your plan involves moving combat troops out, two brigades a month, 16 months, out if Iraq and then beginning to build more troops on the ground in Afghanistan. Is that something - part of that plan involves residual forces, leaving some people behind in case things go wrong, I guess, or to protect American diplomats. What do you mean when you say residual force?

SEN. OBAMA: Well, this is one of the things I want to discuss when I travel there. And I think that it's important to have the commanders on the ground help to shape what is going to be necessary for limited missions that have been defined by the president, the commander in chief. The missions that I've called for: as you said, protecting diplomatic forces and civilians, U.S. civilians or foreign civilians in Iraq, making sure that we are protecting our bases, training Iraqi forces, if, as long as we are short of the fact that we are not training them to engage in sectarian war but rather training them for the integrated force structures that are needed to protect them, and to have a counterinsurgency force that can act swiftly if you start seeing the reemergence of al Qaeda in Iraq. Those would be the limited missions that they would be carrying out. I think we need to make sure that the commanders have the resources they need in order to be able to deal with those issues.

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MS. IFILL: That's a final question, just to - I want you to think a little bit about the stage that you're at in your campaign. You have 26 percent of people still think you were raised a Muslim. People look at your shifts on issues, from warrantless surveillance to gun control, and they say, who is this guy? What does he believe? How do you begin to, in this stage in your campaign, tell people who you are and have it stick?

SEN. OBAMA: Well, first of all, I do think that this notion that somehow we've had wild shifts in my positions is simply inaccurate. You mentioned the gun position. I've been talking about the Second Amendment being an individual right for the last year and a half. So there wasn't a shift there.

MS. IFILL: Campaign finance?

SEN. OBAMA: Well, campaign finance, there's no doubt that that was a shift in recognizing that we could not broker a deal with the Republicans that would prevent the Republican National Committee or the Republican Governors Association or all these other organizations, that are already spending millions of dollars against us, that we could not contain them within a public financing system. So the broader point, Gwen, is if you compare sort of my shift in emphasis on issues that I've been proposing for years, like say, faith-based initiatives, which have raised questions in the press, if you compare that to John McCain -

MS. IFILL: And raised hackles among some of your supporters.

SEN. OBAMA: Well, raised hackles amongst some in the blogosphere, if you compare that to John McCain's complete reversal on oil drilling, complete reversal on George Bush's tax cuts, complete reversal on immigration where he said he wouldn't even vote for his own bill, that I think is a pretty hard case to make that somehow I've been shifting substantially relative to John McCain.