In the first hour or so of the Republican presidential candidates debate conducted by ABC News at Drake University in Des Moines, we saw the most contentious, negative debate of the campaign. It is just 24 days from the Iowa precinct caucuses, and at least a few of those days—Christmas Eve, Christmas, New Year’s Eve and New Year’s Day—are off limits to politics. Candidates who had been willing to hang back and speak positively in earlier encounters suddenly seem to be feeling the pressure to knock down one or more of those rivals who appear to be standing in their way.

Michele Bachmann, whose campaign cannot survive a disappointing showing in Iowa—she doesn’t even have a headquarters in New Hampshire, and her website’s list of New Hampshire news items are all datelined Iowa—went after Newt Gingrich and Mitt Romney for their support, in different ways and different times, of individual mandates to buy health insurance. Rick Santorum, the only candidate to have held events in all 99 counties in Iowa, went after Bachmann hard, contrasting his record on having prevailed on conservative initiatives, even while in the minority in Congress, with hers as not having prevailed. Mitt Romney, running second or tied for second in polls in three of the four January contests, took on both Gingrich (on his space programs, his attack on child labor laws) and Rick Perry (on the Texas mandate for HPV vaccination of teenage girls). Ron Paul proved quite ready to redouble the criticisms of Gingrich he has been making in Iowa ads. Rick Perry made the point, obviously aimed at Gingrich, that you can’t trust people who violate their marriage vows — vows made, as he pointed out, not only with one’s spouse but also with one’s God (that’s even stronger, he said, than a handshake in Texas). Gingrich for the most part refrained from harsh criticism. But he wasn’t shy about saying that Mitt Romney would have also been a career politician these last 17 years if he had beaten Ted Kennedy in his 1994 Senate race.