Associated Press
Donald Trump smiles at left as Republican presidential candidate, former House Speaker Newt Gingrich talks to media after their meeting in New York, in this Dec. 5, 2011 file photo.

LAS VEGAS — Three Republican officials are telling The Associated Press that Donald Trump intends to endorse Mitt Romney's presidential bid. Trump plans to make the announcement Thursday afternoon at his casino hotel in Las Vegas.

The surprise development comes even though Newt Gingrich had informed close advisers Wednesday night that he had expected to win the real estate developer's support.

The GOP officials spoke on the condition of anonymity so as not to pre-empt Trump's announcement.