Has it really been three weeks since the last Republican presidential debate? The campaign has churned up plenty of drama during that time, even without a television faceoff -- but it will still be good to see the familiar ensemble of GOP hopefuls together again onstage Wednesday night.

After the last debate, Herman Cain soared briefly to the top of the polls -- only to be hit with allegations of sexual harassment in his old job as chief executive of the National Restaurant Assn.

The debate at Oakland University in Michigan is supposed to focus on economic policy, an appropriate subject for a Rust Belt state with 11% unemployment. But CNBC’s moderators will find it hard to resist asking Cain if he’d like to clear up the sexual harassment issues once and for all.

Cain’s response is easy to predict; he’s likely to repeat his position that the allegations are false and urge everyone to focus on more important issues. The real challenge is for the other candidates: Should they denounce Cain for his erratic responses to the charges, express sympathy for his predicament, or stay as far away as they can? Expect a lot of the third option, even from Mitt Romney, who this week said the charges were “serious” and “have to be addressed.” Every candidate in the race hopes to inherit the votes of those Republicans who were flirting with Cain; if the former pizza magnate is falling on his own, his rivals’ best strategy is to get out of his way.
Romney, who’s back on top of the polls, faces a different challenge. He has opposed the federal bailout of the automobile industry -- a logical position for a small-business Republican, but a hard one to argue in Michigan. Paradoxically, though, it’s an opportunity for the former Massachusetts governor: A strong defense of his existing position might reassure wary conservatives that he’s not the flip-flopper he’s made out to be.

Former House Speaker Newt Gingrich, who has ticked up in the polls, has a chance to claim his turn for a serious tryout as the conservative alternative to Romney after the rise and fall of earlier contestants.

Texas Gov. Rick Perry, after a string of underwhelming debate performances, needs to regain his footing in the race. But Perry has acknowledged openly that debating isn’t his strong suit; he’s playing for a tie, not a win.

Minnesota Rep. Michele Bachmann, libertarian champion Texas Rep. Ron Paul, former Pennsylvania Sen. Rick Santorum and former Utah Gov. Jon Huntsman Jr. will round out the cast.