SCOTTSDALE, Ariz. — Mitt Romney all but seized control of the Republican Party on Friday, rallying party leaders from around the country with a vow to draft every one of his many rivals into waging the campaign against President Barack Obama and the Democrats.

Meeting in Scottsdale, most party officials were careful not to declare Romney as their nominee, since he still is short of the delegates needed to clinch the nomination and still has two nominal rival candidates — Newt Gingrich and Ron Paul — waging symbolic challenges.

But the party leaders gave Romney a hero’s welcome and, with 2008 nominee John McCain there to salute him, he treated his appearance as a passing of the baton. He was the only candidate who appeared at the gathering.

“Now the great work begins,” said Republican National Committee Chairman Reince Priebus, who presided over the meeting of state party leaders and state-based members of the Republican National Committee.

“We want to welcome you in a formal way to a great family here that is willing and looks forward to working beyond anyone’s imagination in making sure that we put a Republican back in the White House,” Priebus said.

McCain, the Arizona senator who has endorsed Romney, heralded him as the new champion of the party heading into the 2012 election.

“I am so gratified to see our party coming together on a solid team that is going to elect him,” McCain said. “I am most proud to have Mitt as our standard-bearer.”

Romney, who also campaigned Friday in Arizona for Latino votes, saluted “the people who had the courage to run for president on our side of the aisle this year, some still running.”

He listed them by name — Michele Bachmann, Tim Pawlenty, Jon Huntsman, Herman Cain, Rick Perry, Rick Santorum and Paul and Gingrich.

“Each is going to play a vital role in making sure that we win in November,” Romney said, though not all have yet endorsed him.

The state-based party officials appeared eager to close ranks behind Romney, especially now that Santorum has dropped the last serious challenge.

“It’s best that Santorum got out before this meeting. Things are going to coalesce now,” said George Schiavone, a member of the Republican National Committee from Vermont.

Still, Romney cannot take conservatives for granted.

“Conservatives are starting to move his way,” said Glen McCall, a member of the Republican National Committee from South Carolina, a state that Romney lost to Gingrich in the primary.

“The running mate will be key,” added McCall, who also is the party chairman in York County, S.C.

“Sarah Palin really galvanized the conservative vote for McCain. Governor Romney’s going to have to get someone to bring in this big base of conservatives.”