LAS VEGAS - With his trademark flair for spectacle, Donald Trump endorsed Mitt Romney for president Thursday on the famed Las Vegas strip - just hours after Newt Gingrich's advisers were spreading the word that The Donald would be anointing him instead.

Trump's endorsement seemed likely to affect this Saturday's Nevada caucuses - and the GOP nomination fight in general - about as much as a Sin City breeze disturbs the real estate mogul's legendary hair. But he managed to create a stir of a different sort, at least for a day.

Romney said he was glad to get the support, but he seemed almost bemused to be caught up in the Trumpian drama.

"There are some things you just can't imagine happening. This is one of them," Romney said with a smile, looking out at the reporters and cameras jammed into the lobby of the hotel complex that bears Trump's name. The real estate mogul had entered to applause, with Romney and his wife, Ann, at his side

"Mitt is tough, he's smart, he's sharp and he's not going to allow bad things to continue to happen to this country we all love," Trump said. He vigorously shook Romney's hand and said, "Go out and get 'em. You can do it."

But the endorsement was just the finale for a puzzling chain of events that began Wednesday when Trump's office announced he would be flying to Las Vegas for a "major announcement" related to the presidential contest. Trump had announced last spring he would not run for the Republican nomination but had hinted as recently as last month that he might run for president as an independent.

What would he say in Las Vegas? Gingrich advisers suggested Trump had sent "signals" that he planned endorse the former House speaker. The Gingrich team began leaking word of an impending endorsement to news organizations including The Associated Press.

Nope. Reporters learned Thursday that Trump would be endorsing Romney instead.

Earlier, on a tour of a Las Vegas manufacturing facility, Gingrich made clear he had gotten the message.

"No," the former House speaker replied when asked if he was expecting Trump's endorsement. He added that he was amazed at the attention Trump was getting.

Romney hasn't always been Trump's man.

In an interview with CNN last April, Trump dismissed Romney as a "small business guy" and suggested Bain Capital, the venture capital firm where Romney made his millions, had bankrupted companies and destroyed jobs.

"He'd buy companies, he'd close companies, he'd get rid of jobs," Trump said.

Romney, for his part, turned down an invitation to participate in a presidential debate that Trump planned to moderate in Iowa in December, leading Trump to cancel the event. And while Romney, like most of the GOP hopefuls, visited Trump at his office in Manhattan to discuss campaign strategy, he slipped in and out of the building without speaking to reporters.

Trump has played an unusually prominent role in the presidential contest since last spring, when he mused publicly about joining the Republican field.

He also stirred controversy and considerable criticism during that time by openly questioning the validity of President Barack Obama's birth certificate, lending credence to the chorus of "birthers" who say Obama was not born in the United States and not eligible to be president. The fuss pushed Obama to release a long-form version of his birth certificate, showing he was born in Hawaii in 1961.

The president dismissed Trump as a "carnival barker" and then memorably skewered him at the White House Correspondents' Association dinner in Washington, which Trump attended.

On Thursday, Romney said he was honored to receive the endorsement, but hoped even more to win the support of Nevada voters. The state holds presidential caucuses Saturday.

Trump, for his part, called Gingrich "a wonderful person" but said he had decided to endorse Romney two weeks ago.

"He's a friend of mine, I like him a lot. I respect him a lot. But this is the way I went," Trump said.

Trump said China policy was a key factor in his decision to back Romney. Trump has often accused China of manipulating its currency and "cheating" the U.S. - a theme Romney has echoed on the campaign trail.

At a later event, Romney criticized the Obama administration on a different point of foreign policy - the possibility of releasing several inmates from the U.S. prison at Guantanamo Bay, Cuba, as an incentive for the Taliban to join peace talks.

"A sign of good faith? Are you kidding me? A sign of good faith to our enemy?" Romney said.

Trump, a multimillionaire and host of a reality show where he famously proclaims "You're fired," said he wasn't worried that his endorsement would hurt Romney, another wealthy businessman whose opponents have criticized as out-of touch.

"I really think he does connect, and he's starting to connect really well," Trump said.

Democrats, for their part, signaled they believe Trump's endorsement of Romney could work against him. The campaign sent out video of the endorsement event on the president's Twitter feed, with no added comment.

Rival candidate Rick Santorum said of the Trump endorsement, with no small amount of sarcasm: "I can't imagine Donald Trump being hypocritical. That would be totally out of character for Donald Trump."

Santorum added: "You know, Donald Trump does things for one reason and we all know what that reason is. And I think people the people of Nevada are smart enough to figure out who they're going to vote for. It's not going to be based on what Donald Trump recommends."

Associated Press writers Kasie Hunt, Shannon McCaffrey and Philip Elliott contributed to this report.