John McCain effectively clinched the Republican nomination for president Thursday when Mitt Romney abandoned his candidacy, leaving Mike Huckabee as a final but minor obstacle to a resolution of the yearlong race.
Romney's exit came in an emotionally charged speech to a boisterous gathering of conservatives whose hostility toward McCain underscored the challenge that he still faces in uniting Republicans often irked by his rebel streak.
Groans erupted among members of the Conservative Political Action Conference gathered in a packed hotel ballroom as Romney announced his withdrawal. To stay in the race, he said, would make it easier for a Democrat to win, "and in this time of war, I simply cannot let my campaign be a part of aiding a surrender to terror."
"This is not an easy decision for me," said Romney, whose eyes welled with tears. "I hate to lose."
The Boston investment tycoon and former governor of Massachusetts went on to say that he "must now stand aside -- for our party and for our country."
With that, McCain lost his closest rival for the nomination, having already dispatched former New York Mayor Rudolph W. Giuliani, former Tennessee Sen. Fred Thompson and a cast of lesser-known contenders.
"As a matter of political practicality, this is over," said Rich Galen, a Thompson advisor.
For McCain, Romney's departure effectively marked the end of a tumultuous struggle for the nomination. McCain started as the front-runner, then plummeted in the polls, went broke and slashed his staff, only to surge back to the top after winning the New Hampshire primary a month ago.
But the party's conservative wing remains reluctant, at best, to embrace its presumptive nominee. The fate of McCain's quest for the presidency now rides in no small part on one question: Will his friction with the party's conservative base offset his broad appeal among independents?
Even as he racked up new support from the GOP establishment -- Senate Minority Leader Mitch McConnell joined McCain's ranks on Thursday -- Republicans openly denounced him at the conference of conservatives.
McCain, who spoke to the group a few hours after Romney, tried to overcome their misgivings. Hundreds of McCain supporters cheered, but they failed to entirely drown out pockets of booing.
"Many of you have disagreed strongly with some positions I have taken in recent years," McCain said. "I understand that. I might not agree with it, but I respect it for the principled position it is."
McCain recited his record fighting abortion, gun control and the government's "hugely expensive" prescription-drug program for the elderly.
In an atmosphere of conservative fury over illegal immigration, McCain's sponsorship of last year's Senate bill providing a path to citizenship for millions of undocumented workers was the prime source of irritation. He told the crowd a top priority would be "to secure our borders first," and solve related problems in a way that "does not encourage another wave of illegal immigration."
But many in the room wondered aloud whether they could vote for McCain in November. Beyond immigration, they questioned his record on tax cuts, the appointment of conservative judges and more.
"We have to make a decision about how strongly we want to defend our conservative principles versus what we think will happen to the country if the presidency goes back to the Democratic Party," said Jim Clark, 61, a technology consultant from Columbia, Md. "It's not an easy road to walk."
Offering himself as a conservative alternative to McCain is Huckabee, a former Baptist minister. Huckabee's popularity among white evangelicals has fueled victories in Iowa, Georgia, Tennessee, Alabama, West Virginia and Arkansas.
"This is a two-man race for the nomination, and I am committed to marching on," said Huckabee, a former governor of Arkansas, after Romney's withdrawal. He said his dedication to "protecting life and traditional marriage," border security, and a new national sales tax to replace income and other taxes would keep him in the race.
Huckabee could score more party delegates in the Kansas and Louisiana contests Saturday and in the Virginia primary Tuesday, but his continued candidacy would only slow, not stop, McCain's march to the 1,191 delegates needed to capture the nomination.
So far, McCain has 707 delegates; Romney, 294; Huckabee, 195; and Rep. Ron Paul of Texas, 14, according to the Associated Press. Which candidate will wind up with Romney's delegates remains a question mark, but advisors to both McCain and Romney said the Arizona senator would soon accrue the necessary number without them.
"It's done, for all practical purposes," McCain advisor Charles Black said.
McCain yanked his Virginia TV ads on Thursday. But as long as Huckabee stays in the race, aides said, McCain will keep campaigning, with stops today in Virginia Beach; Wichita, Kan.; and Seattle.
Romney's departure came two days after McCain swamped him in Super Tuesday contests around the nation. It was the last in a monthlong string of disappointments for Romney. Most pointedly, he lost hard-fought contests in Iowa, New Hampshire and Florida.
Romney poured more than $35 million of his family fortune into the campaign last year and raised more than $54 million in donations.
He campaigned as a staunch conservative but faced repeated attacks for having shifted to the right on abortion, immigration and gay rights.
By Wednesday evening, Romney was strongly leaning toward dropping out of the race after meetings at his Boston headquarters with advisors and conversations with his wife and sons at the family's home in Belmont, Mass., said senior advisor Tom Rath.
"This is not a person that does things that are futile," Rath said.
Given the delegate tally after Super Tuesday, "it would have been very, very difficult under these circumstances to keep going," Rath said.
In his farewell speech, which could foreshadow an eventual return to political life, Romney lamented "the attack on America's culture," and castigated liberals for fostering welfare dependency.
"The attack on faith and religion is no less relentless," he said, going on to assail "tolerance for pornography, even celebration of it, and sexual promiscuity."
"It would mean attacks on America, launched from safe havens that would make Afghanistan under the Taliban look like child's play," he said. "About this, I have no doubt. Now, I disagree with Sen. McCain on a number of issues, as you know. But I agree with him on doing whatever it takes to be successful in Iraq, and finding and executing Osama bin Laden. And I agree with him on eliminating Al Qaeda and terror worldwide.
"Now, if I fight on, in my campaign, all the way to the convention -- I want you to know, I've given this a lot of thought -- I'd forestall the launch of a national campaign and, frankly, I'd make it easier for Sen. Clinton or Obama to win."
Times staff writers Janet Hook, Seema Mehta, Joe Mathews and Dan Morain contributed to this report.