Republican John McCain asked disgruntled conservatives to support his presidential bid on Thursday, shortly after Mitt Romney ended his struggling campaign and made McCain the all-but-certain nominee.
McCain assured a conference of conservative activists he was one of them, citing his commitment to win in Iraq, halt Iran's nuclear ambitions and rein in the federal government while drawing sharp contrasts with potential Democratic opponents Hillary Clinton or Barack Obama.
McCain's speech, which drew boos on the topic of illegal immigration, followed by a few hours Romney's surprise announcement at the conference that he was ending his run to allow Republicans to focus on the November election.
"I feel I have to now stand aside, for our party and for our country," the former Massachusetts governor told the shocked crowd, some of whom gasped and shouted "No, no!" in response.
McCain, who has built an almost insurmountable lead in delegates to the party's nominating convention, pleaded for party unity during his appearance at the annual conference.
McCain, the 71-year-old former Vietnam prisoner of war, has become a target of critics on the right for his moderate views on illegal immigration, his votes against President George W. Bush's tax cuts in 2001 and 2003 and his labelling in 2000 of some religious conservative leaders as "agents of intolerance."
"I know I have a responsibility, if I am, as I hope to be, the Republican nominee for president, to unite the party and prepare for the great contest in November," the Arizona senator told the activists gathered in a Washington hotel.
"And I am acutely aware that I cannot succeed in that endeavour, nor can our party prevail over the challenge we will face from either Senator Clinton or Senator Obama, without the support of dedicated conservatives," he said.
Romney pulled out after losing 14 of 21 states on Tuesday, the biggest day of U.S. presidential voting ahead of November's election, while McCain romped to coast-to-coast wins and cemented his position as front-runner.
Former Arkansas Gov. Mike Huckabee, who won five states on Tuesday, remains in the race but will have a difficult task overcoming McCain, who has rolled up more than 700 of the 1,081 delegates needed to win the nomination.
"This is a two-man race for the nomination, and I am committed to marching on," Huckabee said in a statement after Romney's withdrawal.
McCain's name was booed by some members of the audience when Romney mentioned him, but he drew mostly cheers when he appeared before the crowd - many of them McCain supporters brought in by the campaign.
