Billionaire businessman Donald Trump is set to endorse Mitt Romney for the Republican Party’s presidential nomination, US media are reporting.
Mr Trump is tipped to announce his support at his Las Vegas hotel later, contradicting earlier reports that he would back Romney rival Newt Gingrich.
The candidates have been campaigning in Nevada after Mr Romney’s resounding win in Florida’s primary on Tuesday.
The eventual nominee will go on to face Barack Obama in November’s election.
Aides from the office of Mr Trump and Republican officials told US media that the real estate tycoon and reality TV star had spoken to Mr Romney on Wednesday night to inform him of the endorsement.
The outspoken businessman flirted last year with the idea of jumping into the presidential race himself as a third-party candidate, but ultimately decided not to.
Mr Trump said on Wednesday that he had an announcement to make about the presidential race, but did not say what it was. US media then reported that he would endorse Mr Gingrich.
Michael Cohen, Mr Trump’s political adviser, declined on Thursday to reveal what his boss would say at the news conference at Trump International Hotel and Tower.
“It’s only a guessing game because the press are making it a guessing game,” said Mr Cohen.
Forme House of Representatives Speaker Mr Gingrich told reporters he had not spoken to Mr Trump for weeks and was not aware of any plans by the businessman to back a candidate.
In an interview with ABC News on Monday, Mr Trump said he was still undecided as to whether to support Mr Romney or Mr Gingrich.
“I like both,” Mr Trump said. “They both want my endorsement. We’ll see what happens but in a very short time I’ll be making an endorsement.”
On Thursday, the candidates were campaigning in the south-western state of Nevada ahead of its Republican caucuses on Saturday.
An opinion poll released by the Las Vegas Review-Journal on Thursday showed Mr Romney, a former Massachusetts governor, leading the pack by 20 percentage points.
He was on 45%, while Mr Gingrich was on 25%, former Pennsylvania Senator Rick Santorum 11% and Texas Congressman Ron Paul 9%.
The Trump development may at least give Mr Romney’s campaign some respite from negative publicity over ill-chosen remarks he made about the poor on Wednesday morning.
During an interview with CNN, the private equity tycoon said: “I’m not concerned about the very poor. We have a safety net there. If it needs repair, I’ll fix it. I’m not concerned about the very rich. They’re doing just fine. I’m concerned about the very heart of America, the 90-95% of Americans who are struggling.”
Mr Gingrich led critics in pouncing on his rival’s remarks about the poor, in an attempt to portray him as out of touch with the lives of ordinary voters.
Mr Romney later told reporters on his plane: “Of course I’m concerned about all Americans… poor, wealthy, middle class, but the focus of my effort will be on middle income families who I think have been most hurt by the Obama economy.”
Nevada’s caucuses on Saturday are the next contest in the state-by-state process of picking a Republican nominee to challenge Democratic President Barack Obama in 6 November’s general election.
The Silver State offers 28 delegates, out of 1,144 needed to clinch the presidential nomination at August’s Republican convention.