BOSTON — Mitt Romney’s shadow looms over a Republican Party in disarray.

The face of the GOP for much of the last year, the failed presidential candidate has been a virtual ghost since his defeat Nov. 6. He has quietly weathered the fallout of the campaign from the seclusion of his Southern California home, emerging only momentarily for a private lunch at the White House with President Barack Obama on Thursday.

His loss and immediate withdrawal from politics, while welcomed by most, has created a leadership vacuum within his party. It’s left the GOP rudderless, lacking an overarching agenda and mired in infighting, with competing visions for the way ahead, during what may be the most important policy debate in a generation.

In his final meeting with campaign staffers at his Boston headquarters, Romney promised to remain “a strong voice for the party,” according to those in attendance. But so far he has offered little to the Capitol Hill negotiations over potential tax increases and entitlement program changes that could affect virtually every American.

He declined to comment on the Treasury Department’s recent refusal to declare China a currency manipulator, which was one of his signature issues over the past 18 months. He made no public remarks after his meeting with Obama, quickly fading away, again.

“If I had to tell you somebody who is the leader of the party right now, I couldn’t,” said Amy Kremer, chairman of the Tea Party Express, which is among the conservative factions vying for increased influence. “There’s a void right now.”

There’s no shortage of Republicans maneuvering to fill it, from House Speaker John Boehner of Ohio to a number of high-profile politicians looking to boost their national profiles, if not position themselves for a 2016 presidential run. That group could include former Florida Gov. Jeb Bush, son and brother of presidents, and New Jersey Gov. Chris Christie.

Republican officials acknowledge party tensions between the moderate and conservative wings, as well as the tea party and evangelical constituencies. But they dismiss the leadership vacuum as a standard political reality for the losing party in the presidential race. Romney, a former Massachusetts governor, never had a strong relationship with the conservative base, given his more moderate past.

Party officials are optimistic that a team of younger and more diverse leaders, drawn from the ranks of governors and Congress, will emerge in the coming months to help strengthen and unify what is now a party grappling with its identity. That list includes Florida Sen. Marco Rubio, and Govs. Bobby Jindal of Louisiana and Nikki Haley of South Carolina.

The GOP was in disarray following its 2006 showing, searching for a new path and leader at a time when President George W. Bush was deeply unpopular.

Arizona Sen. John McCain, the 2008 presidential nominee, briefly assumed control of a party that he long had criticized, but it never really warmed to him. He lost to Obama, and shortly after that, the party turned to an African-American official, Michael Steele, to serve as its chief spokesman. But the decision was widely seen as a mistake, as Steele, a former Maryland lieutenant governor, presided over major financial problems as head of the Republican National Committee.

All that created a leadership vacuum that helped give rise to the tea party movement in 2009 and sparked rounds of internal battles between party pragmatists and more extreme conservatives.

Republican strategist Phil Musser is among those suggesting that the current void presents a breakout opportunity for the party chairman, Reince Priebus. The 40-year-old Midwesterner largely played a supporting administrative role in his first two years on the job.

“To some degree it’s a challenge in as much you don’t have a standard bearer to rally behind that unifies central themes of the conservative movement,” Musser said. “The bottom line is that a little bit of messiness and frank family discussion is not a terrible thing after an election like this.”

But Democrats are emboldened, both by their Election Day successes and the subsequent Republican discord.

GOP factions are fighting over multiple issues: the “fiscal cliff,” which will dominate the debate on Capitol Hill at least through the end of the year; blame for Romney’s defeat; and how to appeal to a shifting and more diverse electorate and unify its message.

The party’s most passionate voters are reluctant to abandon hard-line immigration policies that have dominated their thinking for years. But Washington-based strategists describe a dire need to win over more Hispanic voters and other minorities who overwhelmingly supported Obama in the swing states that decided the election.

At the same time, rank-and-file Republicans on Capitol Hill are struggling to coalesce behind a single message during fiscal cliff negotiations that have exposed a new rift with fiscal conservative guru Grover Norquist and his anti-tax pledge.

There’s also evidence that the fight isn’t over between the conservative and pragmatic wings of the party in Senate primaries.

Conservatives wasted little time signaling that they would work to defeat Shelley Moore Capito, a popular congresswoman from a storied West Virginia political family, as she seeks the nomination for the chance to challenge Democratic Sen. Jay Rockefeller in 2014. Within an hour of Capito’s announcing her candidacy, the deep-pocketed conservative Club for Growth branded her as the “establishment candidate” whose record in Congress of supporting prominent bailouts has led to bigger government.

Democrats already are working to exploit the GOP divisions to strengthen their own political standing.

Obama has taken his party’s message directly to voters. He visited a Pennsylvania toy manufacturer on Friday, calling for Republicans to embrace the immediate extension of tax cuts for all but the top 2 percent of wealthiest Americans.

Though Boehner has taken the lead in negotiations with the White House, Republicans generally did not have a standard-bearer to counter that message. Instead, they’re relying on familiar Capitol Hill leaders to guide party doctrine during his debate.

“We don’t have one person out there carrying that torch. You’ll have (South Carolina Sen.) Lindsey Graham, Speaker Boehner, (Wisconsin Rep.) Paul Ryan, John McCain — same old, same old,” said Republican strategist Hogan Gidley, a senior official on former Pennsylvania Sen. Rick Santorum’s unsuccessful presidential bid. “Void of a singular leader, we’re going to have to rely on some of the younger more dynamic speakers to go out and make our argument.”

No one, it seems, is talking about Romney assuming any sort of leadership role.

“I don’t think that we need to be looking toward Mitt Romney to articulate our principles,” said Jenny Beth Martin, co-founder and national coordinator for the Tea Party Patriots.

It appears Romney may cooperate, choosing business over politics in defeat.

The former businessman is subletting office space at the Boston-area venture capital firm, Solamere Capital, which was founded by his oldest son. Former aides expect Romney to stay out of the spotlight for the foreseeable future — spending colder months at his California home and warmer months at his New Hampshire lake house.

“It might be better for him, better for the party, to start fresh,” Gidley said.