Washington ? John McCain sought to mend his tattered relationship with conservatives and unify a splintered GOP as he all but clinched the party’s presidential nomination Thursday. Mitt Romney, his former chief rival, dropped out, and a parade of prominent Republicans swung behind the Arizona senator.

“We’re continuing campaigning and not taking anything for granted,” McCain said in an Associated Press interview, still reluctant to call himself anything more than the front-runner. “I certainly think that we have enhanced our chances.”

Only Mike Huckabee and Ron Paul remained in what has been a crowded and wide-open nomination fight for the past year. Both have narrow voting constituencies and are far behind in the hunt for delegates to the GOP’s nominating convention this summer.

Romney’s departure left McCain, whose independent streak rankles many in the Republican rank-and-file, poised to assume President Bush’s position as the party standard-bearer. It was a remarkable turnaround for McCain, whose campaign was barely alive last summer, out of cash and losing staff.

“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,” McCain told a gathering of the party’s influential right flank on Thursday a few hours after Romney appeared before the same group to announce he was suspending his faltering bid.

Said Romney, “I must now stand aside, for our party and our country.

“If I fight on in my campaign, all the way to the convention, I would forestall the launch of a national campaign and make it more likely that Senator (Hillary Rodham) Clinton or (Barack) Obama would win.”

Romney’s fate had been virtually sealed earlier this week when he failed to stop McCain’s coast-to-coast Super Tuesday rout in presidential primaries; McCain and Romney spoke by phone Thursday but no endorsement was sought nor offered.

With weekend contests in Louisiana and Kansas up next, McCain has secured 707 delegates, more than halfway to the 1,191 needed to win the nomination. Romney has 294 and Huckabee 195. Paul, the libertarian-leaning Texas congressman, had only 14 – and no chance to catch McCain.

Huckabee is still mathematically viable in the race, but he will need a lot of help from Romney’s supporters if he doesn’t prevail in upcoming contests. Numbers aside, Huckabee also faces a steep challenge. The former Arkansas governor’s primary constituency is Christian evangelicals, and he has won only in states where they dominate presidential contests – Iowa, Arkansas, Alabama, Tennessee, West Virginia and Georgia.

Privately, some Huckabee aides were eager to see their boss follow Romney’s lead. Publicly, Huckabee showed no sign of backing down.

“I still believe that this thing is a long way from being settled. And, now that the field is down to two, our chances have substantially improved,” he said.