LAS VEGAS — After repeatedly flirting with his own presidential bid last year, business tycoon Donald Trump on Thursday picked someone else as his stand-in, endorsing fellow businessman Mitt Romney.
“Mitt is tough, he’s smart, he’s sharp. He’s not going to allow bad things to continue to happen to this country we all love,” Mr. Trump said at his resort, the Trump International Hotel Las Vegas. “Governor Romney, go out and get ‘em. You can do it.”
That was the flashiest endorsement, but not the only one of the day as Mr. Romney and three other Republicans seek the GOP’s presidential nomination. Former Sen. Rick Santorum accepted the support of Sharron Angle, a tea-party favorite and Republicans’ 2010 Senate nominee in Nevada who failed in her bid to unseat Sen. Harry Reid, the chamber’s top Democrat.
She cited Mr. Santorum’s “continuous opposition to amnesty, Obamacare, the bailouts, and cap and trade” as reasons he’s a good pick for tea party enthusiasts.
Analysts increasingly question the value of endorsements — South Carolina Gov. Nikki Haley’s backing didn’t keep Mr. Romney from losing badly in that state’s primary last month — but they draw attention, and none more so than Mr. Trump’s.
Mr. Romney stood by his side, accepting the endorsement with what seemed like bemusement, and at one point even referring formally to his host as “Mr. Trump.”
“Some things you just can’t imagine happening in your life. This is one of them,” Mr. Romney said.
The affair had a bit of a reality-show air to it. Earlier in the week aides to Newt Gingrich, another of the candidates seeking the GOP’s nomination, told reporters they’d been asked to clear off part of his schedule — presumably to accept an endorsement.
But by Thursday morning word leaked that Mr. Romney was the choice.
Mr. Trump has a high public profile and the endorsement will earn headlines, but he does not bring a political operation or any of the other benefits that come from endorsements of longtime politicians.
Rep. Ron Paul’s campaign summed up the endorsement with a question to reporters: “Please explain to us why anyone would care?”
Mr. Trump’s endorsement brings baggage. During his flirtation with a presidential bid he questioned whether President Obama was born in the U.S. to make him eligible to be president. He even said he’d sent investigators to Hawaii to look into the situation.
In response Mr. Obama, who earlier released the “short-firm” birth certificate from Hawaii, released the longer version in April.
On Thursday, the White House laughed off the news of Mr. Trump’s endorsement, with press secretary Jay Carney cracking jokes that made fun of Mr. Trump’s hair.
“I think the president gave his views about Mr. Trump at the dinner that many of you attended last spring,” Mr. Carney said, referring to the White House Correspondents Association dinner when the president joked about the investigation, comparing it to conspiracy theories about a faked moon landing in 1969 or aliens landing in Roswell, N.M.
Mr. Trump, who was in attendance at the dinner, sat through the roasting with a smirk.
At his endorsement announcement on Thursday, Mr. Trump didn’t go into details about why he was backing Mr. Romney, but earlier in the day he told reporters he liked Mr. Romney’s focus on pushing back against China’s trade and monetary practices.
In laying out his economic policies here in Nevada last spring, Mr. Romney had singled out China, saying it was cheating by holding the value of its currency down.
• Dave Boyer, reporting from Washington, contributed to this article.