The Obama campaign is already going up with a new ad in the seven key swing states hitting Mitt Romney for misleading people about his tax plan last night. The spot is a first glimpse into how the Obama campaign will adapt to the Romney we saw at the debate, after the President got caught badly flat-footed in his crosshairs:

The ad’s approach is straightforward: It corrects Romney’s obfuscations with facts. It shows Romney claiming his plan won’t cut taxes by $5 trillion, then points out that the nonpartisan Tax Policy Center found that it would, in fact, cost $4.8 trillion over 10 years.

“Why won’t Romney level with us about his tax plan, which gives the wealthy huge new tax breaks?” a narrator asks. “Because according to experts, he’d have to raise taxes on the middle class — or increase the deficit — to pay for it. If we can’t trust him could we ever trust him here?” During that last line, you see Mitt on the debate stage, and then a shot of the Oval Office.

At yesterday’s debate, Obama repeatedly appeared genuinely flummoxed by Romney’s claims about his own plans, and he did a poor job of adapting to Romney’s strategic obfuscation. As E.J. Dionne points out, Romney last night executed an impressive pivot away from the ideological approach he championed to get through the GOP primaries, and Obama, struggling to keep pace, spent too much time wandering around in a labyrinth of policy arguments and not enough time attacking, exposing, and clarifying the true nature of the ideological differences between the two men.

Obama badly botched things last night. But Obama and his team hope to salvage something from the wreckage: They believe Romney is now on video evading the implications of his own policies in a way that will expose him to tougher scrutiny in the days ahead, giving them more ammo to sow doubts about the true priorities driving Romney’s policies and whose interests they would really advance and protect. The problem for the Obama team is that Romney proved last night that he is capable of concealing the true nature of his agenda quite brilliantly. The pressure is on the Obama campaign to expose it. This ad is a first stab at it, and hints at more to come.