Here's something else that could create political complications for John McCain in key swing states as he continues to defend measures that would maintain tax breaks for the oil industry: He recently opposed extending tax breaks for the wind-power industry.

Making this more difficult for McCain, the fledgling wind-power industry is popular in key upper Midwest and central plains states -- and here you have McCain protecting such tax breaks for Big Oil, but opposing them for Big Wind, or, if you prefer, Little Wind.

McCain recently opposed the big $300 billion farm bill, which itself is extremely popular throughout the upper midwest, describing the bill as "a $300 billion, bloated, pork-barrel-laden bill" because of subsidies for industries like ethanol.

But in a little-noticed development, the bill also contained a measure extending a tax break for developing wind power, which McCain specifically opposed. Obama backed it. According to Senator Tom Harkin, an Obama ally, the wind energy industry is employing close to 2,000 people, some concentrated in those key swing states. It's little local issues like these that can move votes in states where the voting is expected to be extremely close.

Making matters more difficult for McCain, Congressional Dems, such as House Speaker Nancy Pelosi, are edging towards supporting that recent bipartisan compromise energy bill that would open up some areas for drilling but repeal Big Oil's tax breaks.

This ups the pressure on McCain, because it forces him to keep defending his opposition to such a compromise, making it easier to tie him to Big Oil.

The slogan writes itself. McCain: Big Oil, yes, Little Wind, no.

Late Update: To clarify, the wind-power trade group says the industry overall employs 50,000 people. Harkin likely meant they employ 2,000 people in Iowa specifically.

Late Late Update: An interesting take from Steve Benen, who adds the crucial context that McCain's position on Little Wind is at odds with his rhetoric.