ATLANTA -- Herman Cain is learning the hard way what it means to face the glare of the national spotlight.
After captivating Republicans hungry for an alternative to 2012 GOP presidential front-runner Mitt Romney, Cain has made a series of stumbles that have left some questioning whether he's ready for the White House.
His words and actions have drawn more scrutiny since his rise in the polls catapulted him into the top tier of the race for the party's white House nomination.
But Cain has sometimes appeared to be in over his head. Consider what's happened over the past week:
_He suggested electrifying a fence along the U.S. border with Mexico to kill illegal immigrants trying to enter the United States. Cain later called it a joke and apologized if anyone was offended by the remarks.
_He said he would negotiate for the release of U.S. prisoners held by terrorists, then reversed himself and said he had misunderstood the question.
_He muddied the water on abortion. He told CNN that while he strongly opposes abortion, "the government shouldn't be trying to tell people everything to do, especially when it comes to social decisions that they need to make." He later issued a statement reiterating his opposition to abortion.
_Amid criticism that his 9-9-9 tax overhaul would force the majority of Americans to pay more to the government, he reworked the plan to exclude the poorest people and to allow some deductions. Backers of Cain's original plan had praised its simplicity, and carving out exceptions could erode that support.
Through it all, Cain has appeared unflappable. He chalks up the reversals to the breakneck pace of the race.
"In a couple of instances ... I misspoke because of the pace of the interview. I don't call it a flip-flop. I'd rather come back and explain to people what I really meant," Cain said Friday after an economic speech in Detroit. "It doesn't send mixed messages. It just shows that I'm willing to correct myself ... if in fact I need to correct myself for clarity. That's what I'm trying to achieve."
For those in the GOP still in search of a candidate to back, his rocky rollout on the national stage has reinforced the view that Cain, who's never won an election, isn't ready for the big leagues.
"I'm looking for someone that's electable and right now I don't think he fits into that category," said 60-year-old Gene Carkeet of Memphis, Tenn., who attended a recent Cain rally there but remains undecided.
Gwen Ecklund, Republican chairwoman in Crawford County, Iowa, said Cain "has had a bad week."
"I do think it made some people take a second look," she said.
Cain's stumbles come as the campaign of rival Rick Perry shows signs of renewed vigor.
The Texas governor has plummeted in public opinion polls as Cain has climbed. But Perry turned in a spirited and combative debate performance at a recent forum in New Hampshire and plans to detail his own tax reform proposal relying on a flat tax under which everyone would pay the same income tax rate.
Cain and Perry are competing for support from tea party groups and evangelical voters.
Ralph Reed, a Republican strategist who founded the national Christian Coalition and now heads the Faith and Freedom Coalition, said Cain is going through the growing pains that come with sudden national exposure.
"It's a learning curve for any candidate who moves from the back of the pack to front of the pack," Reed said. "You undergo the political equivalent of a GI tract exam ... where every word is weighed and chewed over and scrutinized."
Reed said that after months of jumping on every media appearance offered, Cain and his staff must now limit his exposure and hammer home carefully honed talking points.
That's a tall order for a man who has spent years as a conservative radio talk-show host, saying what was on his mind and scoring points for being provocative.
Whether Cain's willingness to retool his 9-9-9 tax plan will be seen as a strength or a weakness is an open question.
"I guess we'll see what the polls say next week," said Grover Norquist, head of Americans for Tax Reform. Norquist had been critical of Cain's original proposal.
Not everyone is disheartened by Cain's missteps. Kay Godwin, co-founder of Georgia Conservatives in Action, said she is still solidly behind him.
""Look at Romney and Perry at the last debate. They can't even be civil to each other on a stage in front of a national audience," Godwin said. "At his core, Herman has the heart to save this country."
Elliott reported from Detroit.