The first debate in which candidates' positions were decided by lot, leaving former Alaska Senator Mike Gravel at center stage, Democratic White House candidates brought some levity, generally steering clear of attacking each other by name.

That's not to say debate moderator George Stephanopoulos didn't try to elicit controversy. With questions about Senator Barack Obama's experience and Senator Hillary Clinton's connections to Washington put to the whole field, front-runners demurred while second- and third-tier candidates went for the jugular.

Clinton, asked whether Obama had the experience to be president, chose instead to focus on her own campaign. Obama defended his experience while side-stepping other questions that gave him the opportunity to take on Clinton. "To prepare for this debate, I rode in the bumper cars at the state fair," Obama said.

It was left to New Mexico Gov. Bill Richardson to score points, pointing out that Clinton represented experience while Obama represented change. "Change and experience. With me, you get both," Richardson said, to laughter.

Early in the debate, former North Carolina Senator John Edwards sought to defend Obama while casting Clinton as part of the Beltway crowd. "She's been in Washington a long time," he said.

As Stephanopoulos probed for differences in the candidates' positions on Iraq, though, Edwards recast the field as unified, calling differences among them minuscule. Republican policies were, he said, at best "George Bush on steroids."

The most heated debate broke out between Delaware Senator Joe Biden and New Mexico Governor Bill Richardson, two veterans of foreign policy. The two clashed on whether residual troops should be left in Iraq and how quickly a withdrawal can be accomplished.

Biden seemed to come out on top, as most other candidates, including Obama and Clinton, agreed with him. "It's going to be messy. There are no good options. There are only bad options and worse options," Obama said.

Iraq will make some headlines, though, as Clinton came closer to apologizing for her 2003 vote to authorize the use of force in Iraq than she has to date. "Looking back on it, I wouldn't have voted that way again," she said.

In the end, the debate brought more laughter than controversy. "I'm making, at this rate, about one mistake a week," Richardson quipped. Virtually every candidate offered a laugh-line or two. Unlike previous gatherings, no candidate invited too much controversy, while no candidate broke out of the pack.

With more than half a dozen Democratic debates to go, this morning's debate will serve primarily to instruct other moderators in new ways of inviting controversy among the field.

Reid Wilson, an associate editor and writer for RealClearPolitics, formerly covered polls and polling for The Hotline, National Journal’s daily briefing on politics. Before joining RealClearPolitics, Wilson served as Deputy Press Secretary for Senator Chris Dodd's presidential campaign. Wilson’s work has appeared in National Journal, Hotline OnCall and the Arizona Capitol Times. He can be reached at reid@realclearpolitics.com