Campaign ads bombard Iowa, as the Republican candidates and their surrogates step up efforts to raise doubts among caucus-goers about their rivals. In some ads, that means going negative.
At least that's the impression coming through from TV ads and candidates' responses, as the clock ticks closer to the Jan. 3 Iowa caucuses.
Some of the ads are positive. Some go after the candidate of the opposing party, President Obama. But as the race for Iowa draws to a finish, with no clear winner in view, the campaigners have stepped up efforts to raise voter doubts about their rivals for the Republican nomination.
Some of the mud-slinging is being done by surrogates, the so-called "super PACs" (political action committees) that can draw unlimited amounts of money from donors.
Watch Ron Paul's ad here:
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