With the presidential contest entering its final days, Mitt Romney and his top advisers are preparing to make a series of personnel announcements as early as next week — immediately after the election — should the Republican nominee win the White House, according to aides who have been working on his campaign and his transition plans.

For months, much of the political jockeying in Washington has revolved around President Obama, as polls appeared to show him heading toward a second term and supporters took his reelection for granted. Several high-ranking Obama officials, including Secretary of State Hillary Rodham Clinton and Treasury Secretary Timothy F. Geithner, made clear their intention to leave even if the president wins, setting in motion a sometimes publicly visible audition process for their successors.

But as the race has narrowed to a dead heat, top Republican officials have stepped up their angling for slots in a Romney administration. And Romney advisers tasked with leading the “Readiness Project,” an internal operation to ensure a smooth transition of power during the 77 days between the election and the inauguration, have assembled short lists of candidates for the highest-level Cabinet and White House staff positions — including the people who would quickly take the helm should Romney win and begin mapping out the rest of his senior leadership staff.

Asked to describe the kind of team Romney would build, one Republican close to the transition planning said it would be “the third Reagan term that we never got.” Other supporters said they are looking for clues as to whether Romney would cater to the ideological right or more to the center, with evidence pointing to both.

Although the Romney campaign says the candidate has made no final personnel decisions, and the formal vetting would not begin until after the election, a picture of a possible Romney administration has begun to emerge — especially on the economic and foreign policy fronts, two areas that will present the winner with immediate challenges.

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Mike Leavitt, a former Utah governor and secretary of Health and Human Services, is heading Romney’s transition team, which is based in Washington, funded with government money and largely independent from the Boston-based campaign. Leavitt is being discussed as a likely chief of staff in a Romney administration, which would signal that Romney wants a pragmatic leader, versed in the ways of Washington, at the helm rather than an ideological firebrand or an outsider. Aides said Leavitt wields unquestioned authority, with lists of candidates for appointments going through him before reaching Romney.

Conflicting pressures on Romney are playing out in his rumored finalists for secretary of state. Robert B. Zoellick, a George W. Bush administration official who recently stepped down as head of the World Bank, is being mentioned as a possible head of the State Department or the Treasury Department.

But conservative Romney allies consider Zoellick too moderate and conciliatory and not as powerful an advocate for American strength abroad as other contenders for national security positions, including John R. Bolton, a Romney campaign surrogate who served as Bush’s ambassador to the United Nations.

Richard S. Williamson, a top foreign policy official in the Ronald Reagan and George H.W. Bush administrations and a senior policy adviser to Romney, is in the mix for a number of foreign policy posts, including perhaps national security adviser.

Romney aides said they are searching for potential appointees not only among those who have served in government but also across corporate America and other sectors removed from politics. The backgrounds of leading candidates are under intense internal review and dossiers are being prepared for Romney’s perusal, said advisers and Romney associates, who spoke on the condition of anonymity to share internal deliberations.    

“There’s a lot of people that we’re looking at who are just great Americans who haven’t been involved with the campaign,” said a Romney adviser with knowledge of the transition planning.

Sen. Rob Portman (Ohio), Romney’s sparring partner in practice debates, is likely to be a top candidate to head the Treasury Department, advisers have said. Portman served as director of the Office of Management and Budget in the George W. Bush administration. Another contender is R. Glenn Hubbard, the dean of Columbia Business School, who chaired Bush’s Council of Economic Advisers and has helped Romney develop his economic agenda.

Former senator James M. Talent of Missouri, who traveled with Romney to London this summer to meet with British officials, is considered the most likely pick for defense secretary. And Dan Senor, chief spokesman in the Bush administration for the Coalition Provisional Authority in Iraq, would almost certainly serve in a national security position, perhaps in the White House. Senor, a senior foreign policy adviser to Romney, was at his side during his July visit to Israel and helped him prepare for the October debates.

 Two other foreign policy advisers to Romney — Mitchell Reiss, the policy-planning chief under Secretary of State Colin L. Powell, and Elliott Abrams, who was a member of Bush’s National Security Council — are seen by Republicans as likely to join the administration, as is Alex Wong, the campaign’s foreign policy director who staffed Romney on his trip overseas.

Another name that has surfaced for a foreign affairs position is Richard Haass, a policy-planning chief under Powell, although — like Zoellick — Haass is not trusted by the more hawkish Republicans. 

Many of Romney’s top campaign aides are expected to move to Washington from Boston should he win. Lanhee Chen, the policy director, could assume a senior position overseeing domestic policy in the White House, according to Republicans close to the campaign. On the political side, senior advisers Eric Fehrnstrom and Kevin Madden are considered likely contenders for press secretary.

Martha Joynt Kumar, a political science professor from Towson University, said she attended a conference in May with top Romney aides, including Leavitt, where they discussed the transition process with White House aides.

Romney’s staff learned “the tasks that lie ahead and the difficulties involved in them,” Kumar said. “And that you need to start early.”

Each candidate will have to fill out forms for security background checks and financial disclosures. And they must answer personal questions to help ensure that nothing in their pasts might embarrass or compromise the administration — or complicate their confirmation process.

This power reset is a Washington tradition every four years, fraught with gossip, internal jockeying and Vegas-style handicapping. This time it comes as the next administration will face negotiating with Congress over urgent tasks, foremost among them solving the debt crisis that threatens to plunge the nation over the “fiscal cliff” that economists said could forestall the economic recovery.

Inside the Obama administration, lobbying efforts are underway for some of the highest-profile cabinet posts. Clinton has long been expected to step down if Obama wins another term, and she said in a recent interview that she would remain only until a successor were in place.

U.N. Ambassador Susan E. Rice had been considered the leading candidate to replace her, but Rice’s involvement in the White House’s rocky public response to the terrorist attacks on U.S. personnel in Libya has compromised her standing. Sen. John F. Kerry (Mass.), who helped Obama prepare for the debates with Romney, is another top contender to head the State Department, as is national security adviser Thomas E. Donilon.

Defense Secretary Leon E. Panetta is expected to retire to his walnut farm near Monterey, Calif., officials said, although he might stick around for a few more months until the battle over the fiscal cliff is resolved. The Pentagon faces $55 billion in across-the-board cuts early next year unless Congress and the White House find a way to offset them.

One Democratic contender to replace him is Deputy Defense Secretary Ashton B. Carter, a Rhodes Scholar with a doctorate in theoretical physics from Oxford and bachelor’s degrees in physics and medieval history from Yale. He was a longtime Harvard faculty member and served in the Clinton administration as assistant secretary of defense for international security policy.

Michele Flournoy, who served for three years as undersecretary of defense for policy, resigned unexpectedly in February to spend more time with her three school-age children. But she has resurfaced during the presidential campaign as a spokeswoman for Obama on national security.

White House Chief of Staff Jacob J. Lew, a former OMB director, is being discussed as a leading contender to replace Geithner in a second Obama term — which would create a vacancy running the White House itself, a job that Donilon could be tapped for if he did not move to State.

Erskine Bowles, former chief of staff to President Bill Clinton, was mentioned as a possible Treasury secretary, having achieved a level of bipartisan support rare in Washington as co-chairman of the Simpson-Bowles Commission, which recommended ways to curb the federal debt. But he has indicated that he is not interested in serving in the Cabinet.

In the past year, there has been increasing speculation that Eric H. Holder Jr. would step down as attorney general in the wake of negative publicity about Fast and Furious, the botched federal gun operation under the leadership of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Sources close to Holder said that Obama has indicated that he would like the attorney general to stay, but if he does not, Department of Homeland Security Secretary Janet Napolitano has signaled that she would be interested in the job. Also mentioned as possible contenders are Massachusetts Gov. Deval L. Patrick and Preet Bhara, the U.S. attorney for the Southern District of New York. 

Craig Whitlock, Anne Gearan and Sari Horwitz contributed to this report.