Donald Trump
© The Associated Press / Jim ColeIn this May 11, 2011 file photo, possible 2012 presidential hopeful, Republican Donald Trump speaks during a luncheon with the Greater Nashua Chamber of Commerce in Nashua, N.H. Trump announced, Monday, May 16, 2011 that he won't seek the Republican nomination.
Donald Trump to self: You're fired.

Out of the presidential race before he was officially in it, the celebrity real estate mogul announced Monday he would not seek the 2012 Republican nomination. He could have won the White House, he said, but instead will continue to steer his business empire and remain host of his reality show Celebrity Apprentice.

The announcement, ending a colorful and attention-grabbing chapter in the unfolding GOP nominating race, surprised some strategists who said Trump had been assembling a campaign team and had been expected to announce his candidacy soon. This spring, Trump had gained considerable attention by stirring renewed controversy over President Barack Obama's Hawaii birth, leading the White House to persuade the state to release a copy of Obama's long-form birth certificate after two years of dismissing the issue.

Trump revealed his decision Monday at a meeting of advertising executives who had come to learn about NBC's fall television lineup. The network had been pressing him for a decision, fearing the loss of millions of dollars in ad revenue if Celebrity Apprentice didn't return next year.

"I will not be running for president as much as I'd like to," Trump said to cheers from the audience.

His office also released a formal statement, in which Trump said he felt confident he could have won both the Republican nomination and a general election showdown with Obama.

"Ultimately, however, business is my greatest passion and I am not ready to leave the private sector," Trump said.

The Republican race lacks a clear front-runner.

Among the top hopefuls are former Massachusetts Gov. Mitt Romney, former House Speaker Newt Gingrich of Georgia and former Minnesota Gov. Tim Pawlenty. The GOP is still waiting to hear whether Indiana Gov. Mitch Daniels, 2008 vice presidential nominee Sarah Palin or Minnesota Rep. Michele Bachmann will get in the race. Mike Huckabee, the former Arkansas governor and 2008 presidential contender, announced Saturday he would not be a candidate this time.

While Trump's consideration of a run was dismissed as a stunt some Republican pundits and lawmakers, several polls showed him at or near the top of the field both nationally and in early voting states. John McLaughlin, a pollster who would have served as the campaign's senior strategist, said he met with Trump last Thursday to finalize plans for a May 25 announcement, three days after the Celebrity Apprentice finale.

"There was a path for him to win. If he got in and showed he was serious, his vote would have doubled and tripled again," McLaughlin said. "His message had resonance because he was the most anti-Obama candidate or potential candidate of the bunch."

However, not all the interest he stirred was positive: In a recent Associated Press-GfK poll, he was the only potential GOP candidate to receive a 50 percent unfavorable rating by Republicans.

Trump floated the idea of a presidential candidacy in both 1988 and 2000 but claimed he was more serious than ever this time, citing the weak economy and deploring what he suggested was a nation in decline. In interviews and on campaign visits to early voting states such as New Hampshire and Nevada, Trump lashed out at China for unfair trade practices and blasted the OPEC oil cartel, which he blamed for the high cost of gasoline.

"The world is treating us without respect, they are not treating us properly," Trump told attendees in a well-received speech at the Conservative Political Action Committee meeting in Washington in February - a theme he would return to repeatedly.

With his flashy New York lifestyle and multiple marriages - his current wife, Melania, is a supermodel 23 years his junior - Trump might have been hard-pressed to convince conservative GOP primary voters he was one of them. But his supporters insisted that in a turbulent economy, voters are looking for a strong manager and business leader as president.

Trump got fresh attention this year for reigniting the "birther" controversy, insisting there were unanswered questions about whether Obama had been born in Hawaii. Trump won admiration from many on the right who have insisted Obama was born overseas and thus ineligible to serve as president.

Despite years of ignoring such claims, Obama finally pressed the state of Hawaii to release his long-form birth certificate last month - an acknowledgement that Trump had succeeded in bringing into the mainstream what had once been a fringe controversy.

At a brief appearance before reporters after the birth certificate was made public, Obama indirectly cast Trump as a carnival barker and the controversy as a sideshow. Trump took credit for the release even though it robbed his fledgling candidacy of a signature issue.

Obama retaliated days later in his monologue at the White House Correspondents Association dinner, where he poked fun at the birth certificate matter while mocking Trump and his show as the TV host watched from the audience.

"Just recently, in an episode of Celebrity Apprentice at the steakhouse, the men's cooking team did not impress the judges from Omaha Steaks," Obama said as Trump sat stone-faced in the same room. "You, Mr. Trump, recognized that the real problem was a lack of leadership. And so ultimately, you didn't blame Lil Jon or Meatloaf. You fired Gary Busey. These are the kind of decisions that would keep me up at night."

A day later, NBC interrupted the airing of Trump's show with word of an Obama announcement - within 45 minutes the president informed the nation and the world that al-Qaida leader Osama bin Laden had been killed.

Whatever buzz that had remained over a Trump candidacy fully faded. In a May 4 Quinnipiac University national poll, 58 percent of voters said they would never vote for Trump for president, including 32 percent of Republicans.

NBC said that The Celebrity Apprentice would be coming back in midseason. The show has averaged 8.9 million viewers an episode this season, up 12 percent over last year, the Nielsen Co. said.