Debate dilemma for GOP hopefuls: Herman Cain or Mitt Romney?

It’s time for another Republican debate and another opportunity for candidates to shake up the state of the race -- if only they can decide which candidate they should target.

A CNN poll released Monday on the eve of its Las Vegas debate showed Mitt Romney just ahead of Herman Cain, 26%-25%, among a national sample of Republican voters. It’s the second poll in less than a week showing the former pizza chain executive and the man with the plan -- “9-9-9” -- near the top of the heap.

But it’s also Romney’s strongest showing in the CNN poll in four months, since before Rick Perry’s name was included. Perry has slipped from frontrunner status at 30% to just 13% support. He’s followed by Ron Paul (9%), Newt Gingrich (8%), Michele Bachmann (6%) and Rick Santorum (2%).

Last week, when the candidates last met for a forum on the economy in New Hampshire, Cain and his “9-9-9” plan seemed to dominate the discussion. But the event, broadcast only on the niche Bloomberg Network and streamed online, likely did not have the same expanded audience that Tuesday night’s CNN event will.

So for the trailing candidates, engaging again with Cain might seem a wise tactic -- particularly with the “anti-Romney” mantle still up for grabs.

But Cain is already beginning to get much greater scrutiny on his own. He was on the defensive during a weekend appearance on “Meet The Press.” He’s stumbled of late when asked about controversial remarks about an electrified border fence -- first saying he was joking, but then seeking to argue it was a real plan.

The Obama campaign has made it clear they don’t think the candidates have been tough enough on Romney, one reason they’ve ramped up their own attack machine. The former Massachusetts governor has seemed to benefit from the fact that every time candidates meet for a debate, there’s a new Republican also-ran surging -- first Bachmann, then Perry, and now Cain.

Romney’s camp seems to think that Perry remains their biggest threat. It released a web video on Tuesday morning highlighting a recent spike in unemployment in Texas. One claim in the video -- nearly half of the new jobs in Texas over the past four years “went to illegal immigrants.”

“Incumbent politician. Bad jobs record. Won’t face the facts -- Sound familiar?” the video asks, pairing Perry with President Obama.

One candidate who’s been a fixture of the more than half-dozen debates, former Utah Gov. Jon Huntsman, is skipping the debate. His New Hampshire-or-bust strategy has him holding a town hall meeting in the Granite State instead Tuesday.