In a surprise twist, Donald Trump endorsed Mitt Romney - not Newt Gingrich - for the Republican presidential nomination. Gingrich's camp had been so confident of winning the real estate mogul's backing that it had leaked word Trump would support the former House speaker.

Trump made the announcement in Las Vegas at the luxury hotel bearing his name, with Romney in attendance. Nevada holds its presidential caucuses on Saturday.

Speaking with reporters before the announcement, Trump said he had several meetings with Romney during the past several months and that those meetings helped influence his decision about an endorsement.

He also cited Romney's debate performances and tough stance on China as reasons.

Trump, who publicly had expressed less-than-enthusiastic support for Romney, said his past comments were a reflection of not knowing the former Massachusetts governor very well.

"I never knew him. I knew of him and respected him, but I really got to know him over the past few months," Trump said. "I've had numerous meetings with him."