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Tea Party favorite Herman Cain announced his long-shot presidential candidacy to a raucous crowd in Atlanta Saturday, yelling, "I'm running for president of the United States and I'm not running for second."

At a rally attended by thousands, the businessman, author and talk radio show host showed he knows how to wow a conservative gathering. The crowd chanted, "Herman, Herman, Herman," as Cain unleashed the same soaring rhetoric and relentless attacks on President Obama that has created buzz in recent weeks.

"Let me tell you some of the reasons why I'm running for president of the United States.We have become a nation of crises," he said, citing morals, the economy, entitlement spending, immigration and foreign affairs as among the crises facing the nation.

"And we've got a deficiency of leadership crisis in the White House," he said to roaring cheers.

Now the 65-year-old Republican will see if he can use that grass-roots enthusiasm to turn a long-shot presidential campaign into a credible bid.

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Cain has been introducing himself to voters during months of traveling around the country.

Cain supports a strong national defense, opposes abortion, backs replacing the federal income tax with a national sales tax and favors a return to the gold standard.

He's never held elected office, losing a three-way Republican U.S. Senate primary bid in Georgia in 2004 with one-quarter of the vote. His "Hermanator" political action committee has taken in just over $16,000 this year.

Cain says he's running "a bottoms-up, outside-the-box campaign." Supporters say he taps into the tea party-fueled desire for plain-speaking citizen candidates.

"I just love him," gushed Laura Miller, a self-described "Cainiac" from Jessup, Ga. "What he says makes so much sense."

Born in Memphis, Tenn., and raised in Atlanta, Cain is the son of a chauffeur and a maid. He attended historically black Morehouse College, earned a master's degree from Purdue University and worked as a mathematician for the Navy before beginning to scale the corporate ladder.

He worked at Coca-Cola, Pillsbury and Burger King before taking the helm of the failing Godfather's Pizza franchise, which he rescued by shuttering hundreds of restaurants.

He burst onto the political stage when he sparred with President Bill Clinton over the Democrat's health care plan at a 1994 town hall meeting.

"On behalf of all of those business owners that are in a situation similar to mine," asked Cain, "my question is, quite simply, if I'm forced to do this, what will I tell those people whose jobs I will have to eliminate?"

The late Jack Kemp, the GOP vice presidential nominee in 1996, once described Cain as having "the voice of Othello, the looks of a football player, the English of Oxfordian quality and the courage of a lion."

In 2006, Cain was diagnosed with liver and colon cancer. He says he's been cancer-free since 2007 and credits the nation's health care system with keeping him alive. He says it's one reason he's so opposed to the health overhaul championed by President Barack Obama.

At a speech last week in Macon, Ga., Cain gave a glimpse of the rationale for his candidacy. He said the American dream is under attack from runaway debt, a stagnant economy and a Democratic administration forcing a legislative agenda citizens don't want.

The Associated Press contributed to this report.