Democrats Barack Obama and Hillary Clinton have escalated their skirmish over a weekend column by conservative columnist Robert Novak who reported “agents” in the Clinton camp were armed with “scandalous information” about Obama. Obama himself struck back Sunday in Iowa, calling the report “slime politics.”

And Obama told a crowd in Cedar Falls that voters should evaluate the “character” of the candidates. ‘That’s the question you have to ask yourself in terms of who the next president’s going to be,” Obama said. “What’s their judgment and what’s their character?”

Meanwhile, Clinton’s campaign suggested Obama had been thrown off his game by a Republican-leaning journalist trying to instigate a fight between the two Democrats. Obama called that “silly.”

Also Sunday, Delaware Senator Joe Biden, another Democratic presidential hopeful, began an 11-day campaign swing through the state. “I’ve seen polls in Iowa saying it’s anywhere from 40 to 70 percent of the people who’ve stated a preference are unsure of their preference,” Biden said. “I intend to win here. I’m not here for the exercise.”

Connecticut Senator Chris Dodd is in Iowa, too, for a campaign swing that will see him spend Thanksgiving Day on a farm near Monticello.

A lone Republican candidate was in the state over the weekend. Texas Congressman Ron Paul says if he does not win the GOP’s nomination, he’s not interested in launching an independent bid for the White House. “I sure haven’t been thinking about it. I have no plans to do that,” Paul says. “It’s like a painful thought.”

Paul ran once before as the Libertarian Party’s presidential nominee in 1988 and wound up getting about two percent support. “When I did it before, I spent half the money just trying to get on the ballots. The laws are very biased and it’s very hard to get into the debates. If the establishment doesn’t want you in the debates, they don’t let you in the debates, so if you don’t get into the debates and you have trouble getting on the ballots then you don’t gain this credibility,” Paul says. “I’ve sort of been able to gain credibility through the back door here, you know, running as a Republican and all of a sudden getting a lot of support, a lot of volunteers and a lot of money. It’s getting pretty hard to be ignored.”

Paul predicts he will have another huge fundraising day on December 16th, the anniversary of the Boston Tea Party. On November 5th, Paul received over $4 million in campaign contributions.