Republican presidential hopefuls were preparing for their latest debate Tuesday night at a Las Vegas casino, with eyes on businessman Herman Cain who has surged to the top of polls in the far-from-decided race.
Cain, the former Godfather's Pizza chief executive, has never held public office, but he's built up a following among conservative activists as a radio talk show host and motivational speaker.
He has been facing more scrutiny as his poll numbers have jumped to put him in a dead heat with the presumed front-runner, former Massachusetts Gov. Mitt Romney. And Cain is ahead of Texas Gov. Rick Perry, who also has conservative support but has stumbled in earlier debates.
All are vying for the Republican nomination to challenge Democratic President Barack Obama in 2012, and many undecided voters have been watching the debates to evaluate the candidates.
Much of the focus Tuesday will be on Cain's catchy "9-9-9" tax overhaul plan which he's made the centerpiece of his campaign. The plan would scrap the current tax code and replace it with a 9 percent tax on personal income and corporations as well as a new 9 percent national sales tax.
Now that he's in the national spotlight, Cain has already had to apologize for comments he made over the weekend calling for an electric fence along the southern border with Mexico.
At a campaign stop Monday in Arizona, Cain appeared with Maricopa County Sheriff Joe Arpaio, an aggressive anti-immigration proponent.
"It was a joke," Cain said emphatically during a news conference. "I apologize if I offended anyone. Mea culpa, mea culpa, mea culpa."
Cain, who is African-American, told an audience in Tennessee on Saturday that the fence is "going to be electrified. And there is going to be a sign on the other side that says, 'It will kill you."'
Immigration already has flared on the campaign trail and contributed to the sinking of another fast-rising Republican candidate. Perry has struggled to explain why he signed a law giving lower in-state tuition breaks to illegal immigrants at Texas universities.
When he first entered the race, Perry was at or near the top of many national polls. He's fallen back since after weak performances in the candidates' debates.
Cain has emerged as the more popular alternative to Romney, who is viewed warily by the party's conservative base for his past support of abortion and gay rights and his championing of a health care reform plan in Massachusetts that was a model in part for President Barack Obama's health care overhaul that Republicans loathe.
In addition to Cain, the others participating in Tuesday's debate at the Venetian Resort Hotel Casino are Romney, Perry, Minnesota Rep. Michele Bachmann, Texas Rep. Ron Paul, former Pennsylvania Sen. Rick Santorum and former House Speaker Newt Gingrich.
Missing is former Utah Gov. Jon Huntsman, who's boycotting the Nevada caucuses in defense of New Hampshire's first-in-the-nation primary.
Nevada has scheduled its contest for Jan. 14, and New Hampshire Republican officials are pressuring Romney and other Republicans to join Huntsman's boycott if Nevada refuses to hold the caucuses later in January.
Obama carried Nevada by a comfortable 12 percentage point margin in 2008 but now is vulnerable in the economically hard-pressed state.
Obama, for his part, has embarked on a campaign style-bus tour through North Carolina and Virginia, mocking congressional Republicans for rejecting his $447 billion jobs bill that combines tax cuts and new spending in an effort to jump start the stagnant economy. Obama won the two traditionally Republican-leaning southern states in 2008 on his campaign's ability to boost turnout among young people and black voters.
In North Carolina, the president directed his most pointed remarks at Senate Republicans, who last week blocked action on the jobs bill.
"Essentially they said 'no' to you," Obama told a supportive crowd outside Asheville. Noting that Republicans will now get a chance to vote on elements of his jobs agenda one by one, he said: "Maybe they just couldn't understand the whole thing all at once. So we're going to break it up into bite-size pieces."
Senate Democrats unveiled the first individual bill taken from Obama's jobs package, which would spend $30 billion to create or save education jobs and $5 billion to do the same for police and firefighters. Republicans are likely to block the bill.
Republicans denounced the bus trip as nothing more than a taxpayer-funded campaign trip through two must-win states to try to bolster Obama's standing for the 2012 election.
Obama's poll numbers are down in both Virginia and North Carolina, languishing in the mid- to low-forties in recent surveys. The numbers mirror his approval ratings nationally.