WASHINGTON — Mitt Romney dropped out of the presidential race Thursday in front of a sympathetic crowd of conservatives, putting an end to his bid to become the first Mormon to win the White House.

"This isn't an easy decision. I hate to lose," Romney told members of the Conservative Political Action Conference, who were expecting to hear just another campaign speech at their annual convention.

His surprising announcement came just two days after GOP front-runner Sen. John McCain, R-Ariz., won a majority of delegates up for grabs on Super Tuesday, making it virtually impossible for Romney to win the nomination.

Romney said he got out now to help his party keep control of the White House in a time of war. He said Democratic presidential candidates Hillary Clinton and Barack Obama "would retreat and declare defeat" while McCain would do "whatever it takes" to succeed in Iraq.

"If I fight on in my campaign, all the way to the convention — I want you to know I have given this a lot of thought — it would forestall the launch of a national campaign and probably make it easier for Senators Clinton or Obama to win," Romney said.

"Frankly, in this time of war, I simply cannot let my campaign be a part of aiding a surrender to terror."

That was a complete turnaround from Romney's election night pledge on Tuesday to keep fighting all the way to the Republican National Convention in September — and to the White House in November.

He apparently realized it was time to call it quits after meeting with his senior campaign team in Boston Wednesday to consider his options after his disappointing performance on Tuesday. He has less than half as many delegates as McCain.

"I was holding out hope," said Romney's national finance director, Spencer Zwick, one of the participants in that secret meeting. "But Super Tuesday changed some things."

Zwick, a Utahn who first worked for Romney as an aide during the 2002 Winter Olympics in Salt Lake City, said "at the end of the day, the final decision was made by Mitt and Ann," Romney's wife of 39 years.

"It is a sad day. It's tough. It's tough," Zwick said. "Nobody likes to say it's better to step aside." But leaving now gives him some goodwill with the party, paving the way for a future presidential run, possibly in 2012.

Campaign spokesman Eric Fehrnstrom said the team "saw a pathway to the nomination, but it would have been difficult."

Romney was scheduled to speak in Baltimore Thursday night at a Republican fundraiser but that appearance was canceled. Campaign advisers suggested it had only been added to the schedule to ensure Romney's announcement Thursday came as a surprise.