CNBC is moderating the debate at Oakland University, which is nestled in a tiny suburb that both supported President Obama in 2008 and, two years later, Republican Gov. Rick Snyder, who has waged war with the state's labor unions.

High unemployment and Europe on the brink set a daunting backdrop for a Republican presidential field without a clear leader.

The debate began not on the US, though, but on Europe, where first Greek's debt and now Italy's have called into question not merely those economies but also the standing of the US.

Worries over Italy help throttle the US financial markets Wednesday. But the candidates insisted that it wasn't the responsibility of the US bail out irresponsible European nations.

"My view is no, no, no. We do not need to step in and bail out banks in Europe or here in the U.S. that may have Italian debt," former Massachusetts Gov. Mitt Romney said.

Texas Rep. Ron Paul said the Italian debt needs to be liquidated, and further warned that the U.S. is on a similar path.

"If you prop it up you'll do exactly what we did in the Depression — prolong the agony," Paul said.

The debate was to focus on the economy, but allegations of sexual misconductagainst Herman Cain have added a salacious element to the contest.

To hoots from the audience, Cain was asked to address the issue of whether he has a character problem that disqualifies him from being able to serve as president.