The Republican National Committee (RNC) is out with a new ad airing in Colorado today that uses President Obama's own words to hammer him for his broken promise to reduce the deficit. 

The video uses Obama's very specific and repeatedly made promise that he will "cut the deficit in half by the end of his first term" juxtaposed against a clock counting up the national debt under Obama — currently over $15 trillion. 

It is this kind of ad, rather than ideological attacks on his renewable energy boondoggles, that could be most damaging because it calls into question Obama’s character.

As a recent study by Stanford University found, voters despise politicians who break promises. The study looked specifically at anti-tax activist Grover Norquist’s no new taxes pledge. Interestingly, the study found that voters will hold it against politicians who break the pledge, even if they don’t support the pledge itself.

The Washington Post’s Ezra Klein explains:

But here’s the real issue: Even if that politician is facing an electorate that wants tax hikes, he’ll lose to a challenger who wants tax hikes and never broke the pledge, and he’ll lose some of his appeal against candidates who want only spending cuts. “Voters who disagree with a pledge are nevertheless willing to enforce it,” write the authors. [Peak emphasis]

So it’s very hard for a politician to find a political upside in breaking the pledge: He loses too much among voters who hate taxes without gaining enough among voters who support taxes. The bottom line, say the authors, is “in the most likely general election scenario, pitting a pledged Republican against an unpledged Democrat, breaking the pledge would hurt the Republican’s electoral prospects unless nearly all voters (98%) wanted higher taxes.”

If the Stanford study can be applied to Obama’s promise to cut the deficit in half, then that could mark big trouble for Obama.