What happened
Barack Obama pulled into a statistical tie with Democratic front-runner Hillary Clinton in Iowa, as the rival presidential candidates stepped up their attacks on each other. A Washington Post/ABC News poll released Monday found that 30 percent of likely Democratic caucusgoers supported Obama, while 26 percent backed Clinton and 22 percent backed former senator John Edwards. (The New York Times' The Caucus blog, free registration)

What the commentators said
Mudslinging seems to have taken over the campaign, said Noam Scheiber in The New Republic Online. At least for the moment. Obama has been “exercised” like never before since columnist Robert Novak wrote that Clinton’s campaign had “dirt” on Obama that it wasn’t going to use. The story has captured "the lurid imagination" of campaign watchers, and that might increase the buzz around his campaign.

This is where the race gets interesting, said Eugene Robinson in The Washington Post (free registration). Rough, negative campaigning “isn’t a pox on the republic,” it’s tradition. And “the swordplay of attack and counterattack” can be helpful, by “getting candidates off their standard, focus-group-tested campaign rhetoric and flushing out their unvarnished views.”

Let’s not let the nastiness get out of hand, said the Seattle Post-Intelligencer in an editorial. Sen. John McCain had a chance to strike a blow for civility when a supporter referred to Clinton as a “bitch,” but he just laughed instead. “If it’s not too late,” the candidates should all try to remember that “how they respond to such digs matters.”

The "politics of strategic outrage" are in full force in both parties, said Mike Allen and Jonathan Martin in The Politico. With the "tight campaign calendar," no one can afford to let an attack pass without a counterattack. And all the candidates want to "show they're tougher than John Kerry was in 2004."