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Mitt Romney suspended his presidential campaign Thursday, telling a stunned conservative group that continuing his uphill battle against John McCain would hurt the Republican Party and make it more likely that the Democratic candidate would win the general election in November.

“If I fight on in my campaign, all the way to the convention … I’d forestall the launch of a national campaign and, frankly, I’d be making it easier for Sen. Clinton or Obama to win,” Romney told the Conservative Political Action Conference. “Frankly, in this time of war, I simply cannot let my campaign be a part of aiding a surrender to terror.”

As early as Wednesday, the Romney campaign was drafting a road map to winning the nomination, despite trailing McCain badly in the race for delegates. But according to a campaign spokesman, Romney decided to drop out as he was writing the CPAC speech late Wednesday. He repeatedly cited the Iraq war effort in his decision, saying he agrees with McCain in his approach to fighting terrorism.

“This isn’t an easy decision. I hate to lose,” Romney said Thursday, as many in the crowd booed the decision. “If this were only about me, I’d go on, but it’s never been only about me. I entered this race because I love America, and because I love America in this time of war, I feel I have to now stand aside, for our party and for our country.”

The news was surely a blow to the CPAC audience, which appeared largely unaware of the former Massachusetts governor’s plan in the minutes before his speech. At least one Romney staffer was crying as he prepared to give his speech.

The decision moves McCain closer to the GOP nomination than he’s ever been. But McCain could get a tense reception when he speaks to the same conservative audience later in the afternoon, as many in the far-right wing of the party have been skeptical of him. He’s been fighting to shore up support among those conservatives.

McCain was not told of Romney’s decision ahead of time and his prepared remarks Thursday made no mention of his rival’s decision.

In the remarks, McCain urges those conservatives who have disagreed with him to nevertheless help him beat the Democrats in November, saying “It is my sincere hope that even if you believe I have occasionally erred in my reasoning as a fellow conservative, you will still allow that I have, in many ways important to all of us, maintained the record of a conservative.”

Radio talk show host Laura Ingraham introduced Romney as the only conservative running for president Thursday.

“I will continue to stand for conservative principles; I will fight alongside you for all the things we believe in. And one of those things is that we cannot allow the next president of the United States to retreat in the face of evil extremism,” Romney said to cheers and applause as he closed his speech.

Click here to see more photos from Romney’s announcement that he will drop his presidential bid.

Campaign aides said Romney was technically suspending the campaign. He had spent an estimated $35 million of his own money to fund the increasingly longshot bid. By suspending rather than quitting he will be able to continue to collect donations from contributors.

But Romney would have been hard-pressed to continue in the race. He has steadily lost ground over the past few weeks to McCain, whose victories on Super Tuesday made a comeback for Romney extremely difficult. Romney’s departure from the race means McCain’s bid is nearly assured.

McCain is leading Romney by nearly 3-1 in the delegate count, 703-293, and Romney also had been losing ground to Mike Huckabee, who picked up nearly as many victories as he did on Super Tuesday.

“One of the biggest barriers to Mitt Romney becoming the nominee was Mike Huckabee,” Time magazine writer Mark Halperin, who was first to break the news, told FOX News. “I don’t think Huckabee stands much of a chance to overtake McCain either, but he certainly stood in Mitt Romney’s way.”

Huckabee’s staffers say they’re staying in the race.

Huckabee national chairman Ed Rollins told FOX News that Romney’s exit “gives us a chance to run and contrast ourselves against McCain.”

McCain still is trying to unite conservatives in an effort to look ahead to the general election. McCain, who traditionally has skipped the big CPAC event, can’t afford to stay away this year. Last year, McCain placed fifth in the CPAC straw poll, behind Romney, Sam Brownback, Rudy Giuliani and Newt Gingrich.

Brownback and Giuliani are out of the race and supporting McCain, but the conservative chorus against him has grown stronger since he began collecting victories in the 2008 Republican presidential primaries.

Evangelical leader Pat Robertson told FOX News Radio Thursday morning that he and other evangelicals would not support McCain, citing his temper.

Robertson referenced a Wall Street Journal article describing him as a “capped live volcano,” adding: “You never know when he’s going to explode. … If you’ve got a guy who’s the commander in chief with his hand on the red button, I just don’t know, I wouldn’t like to be in WWIII, and I just have a feeling he wants to show how macho he is and we might just get ourselves in something we don’t want.”

Other conservatives take issue with his more moderate stances on illegal immigration, global warming and other matters.

But McCain, known for his independent streak, still could sell his conservative credentials, which include hawkish national security positions, a 100 percent anti-abortion record, appointing constitutionalist judges to the bench and fiscal discipline.

Romney’s departure from the race came almost a year after his formal entrance, when the Michigan native declared his candidacy on Feb. 12, 2007, at the Henry Ford Museum of Innovation in Dearborn, Mich.

Over the ensuing 12 months, Romney sought the support of conservatives with a family values campaign, emphasizing his opposition to abortion and gay marriage, as well as his support for tax cuts and health insurance that would benefit middle-class families.

He sought to cast McCain as being outside the mainstream of conservative thought, but McCain traded with charges that Romney was a flip-flopper on social issues.

Throughout his campaign, Romney was questioned by voters and the media about his Mormon faith. Hoping to assuage voters skeptical of electing a Mormon president, Romney spoke on Dec. 6 in College Station, Texas, explicitly recalling remarks John F. Kennedy made in 1960 in an effort to quell anti-Catholic bias. He vowed to serve the interests of the nation, not the church, if elected president.

Romney’s original goal was to score back-to-back wins in Iowa and New Hampshire, clearing the field and creating momentum to roll through Florida — where he enjoyed the support of top aides to former Gov. Jeb Bush — and seal the nomination in the Super Tuesday contests.

Instead, Romney was beaten Jan. 3 in Iowa by Huckabee, an ordained Baptist minister who received an unexpected outpouring of support in the caucuses from voters identifying themselves as evangelicals.

Five days later, Romney suffered a second consecutive defeat in New Hampshire, when McCain won the primary in part with the support of independents attracted to his self-styled maverick campaign.

He won the Michigan primary and Nevada and Wyoming caucuses early on, but his seven victories on Super Tuesday were not enough to compete with McCain’s wins in delegate-heavy states like New York, New Jersey and California.

Romney canceled a campaign event in Baltimore Thursday night and planned to head to Massachusetts to get some rest.

FOX News’ Shushannah Walshe and Serafin Gomez and The Associated Press contributed to this report.