Republican presidential contenders piled on the two front runners in a feisty debate Tuesday night, attacking businessman Herman Cain's centerpiece economic plan as a tax increase and former Massachusetts Gov. Mitt Romney over his health care reform law.
Cain, a former pizza company CEO is the latest and unlikeliest phenomenon in the race to pick a Republican rival for President Obama. A black man in a party that draws few votes from Africans Americans, he had bumped along with little notice as Romney sought to fend off one fast-rising rival after another from the party's right flank.
That all changed in the past few weeks, after Texas Gov. Rick Perry burst into the race and then fell back in the polls after a series of weak debate performances. However unlikely Cain's rise, Tuesday night's debate made clear that none of his rivals are willing to let him go unchallenged.
The candidates' debate - the fifth in six weeks - ranged over familiar and contentious territory - from immigration and health care reform to the economy and energy, often in antagonistic terms. The candidates engaged each other more directly and sometimes more heatedly than in previous debates.
But Cain's surprising rise from the bottom of the pack in the polls to top-tier contender was clearly on the minds of his rivals on stage in a hotel along the Las Vegas Strip.
While polls chart a series of rises and falls for various contenders, Romney has consistently remained at or near the top but with fairly static numbers. The other contenders are jockeying to be the conservative alternative to Romney who is viewed warily by many in the party's base for his past support of abortion and gay rights and his championing of a health care reform plan in Massachusetts that served as a model in part for Obama's healthcare overhaul that Republicans loathe.
Fact checking the GOP Vegas debate
Much of the focus was 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.
The other candidates tore into Cain with one citing an analysis published Tuesday that found taxes would go up for 84 percent of American households under the "9-9-9"plan.
Minnesota Rep. Michele Bachmann who also enjoyed a quick rise - after a strong debate performance in New Hampshire - and a quick fall when national support didn't develop, went on the attack in an attempt to stay in the race, calling Cain's plan a value added tax that would cause prices to snowball as products moved up the production line.
Undeterred, Cain insisted the charges were untrue and blamed the criticism on lobbyists, accountants and others who "want to continue to be able to manipulate the American people with a 10-million- word mess," the current tax code.
Texas Gov. Rick Perry, who was embraced by many Republicans when he announced his bid in August, but has faded after a series of missteps, used the debate to set his sites on Romney.
He accused Romney of being dishonest about his record on the health care law that he instituted as governor of Massachusetts. Perry sought to play on conservative suspicions that Romney was too
moderate and inconsistent, declaring early on: "I'm an authentic conservative not a conservative of convenience."
Perry also sought to attack Romney over immigration, saying that he had no credentials on the issue because he had once hired an illegal immigrant, the "height of hypocrisy."
Romney denied the charge, saying he had hired a company to mow his lawn and did not know that it had illegal immigrants on its payroll.
On a more substantive level, Perry said he opposed repealing the portion of the 14th Amendment to the Constitution that says anyone born in the United States is automatically a citizen. In previous debates, Perry had come under criticism for being soft on immigraiton for supporting a Texas law that granted lower in-state college tuition rates to illegal immigrants.
Cain found himself on the defensive on two others issues during the two-hour debate.
He apologized for earlier remarks about building an electrified fence along the Mexico border that could kill people trying to cross illegally.
And he said he wouldn't be willing to negotiate with terrorists, even though he suggested he might be in an interview earlier in the day.
Foreign policy took a secondary role in the debate.
Libertarian-leaning Texas Rep. Ron Paul said U.S. troops should be withdrawn from Korea - where they have been stationed for more than 50 years - and foreign aid to Israel cut.
Perry said it was "time to have a very serious discussion about defunding the United Nations."
Former Utah Gov. Jon Huntsman skipped this debate, saying he was boycotting the Nevada caucuses in a dispute over the primary and caucus calendar. He is campaigning exclusively in New Hampshire in hopes that a strong showing there can move him into the thick of the race.
Not only Republicans, but Mr. Obama was also critical of Cain's economic plan during the day.
In an interview with ABC News, Mr. Obama said Cain's plan would be a "huge burden" on middle-class and working families.