WASHINGTON -- Gone is the private jet and the motorcade that swept him from the tarmac to the private hotel entrances. His security staff has been reduced to a few Capitol Police officers, soon to fade away. Representative Paul D. Ryan of Wisconsin is back to driving his own truck back home, and walking to the House floor here for votes alone, like everyone else.
But while the campaign trappings and the high profile of the national campaign are behind him, Mr. Ryan now finds himself at the center of one of the biggest fiscal negotiations in a generation.
Speaker John A. Boehner has tapped Mr. Ryan, who has returned to his post as the House Budget Committee chairman after an unsuccessful run for vice president, to help strike a deal to avoid big tax increases and spending cuts by the end of the year, and to bring along fellow Republicans.
"He helps us toward creating a product," said Senator Rob Portman, Republican of Ohio, "and he helps sell the product."
The test will be whether Mr. Ryan -- who declined last year to sit on another Congressional committee charged with taming the deficit, in large part because doing so might have hurt his prospects for national office -- can make the transition from House budget philosopher to governing heavyweight who can help negotiate a bipartisan deal and sell it to his colleagues.
While President Obama and the Democrats are expected to give ground on entitlements and discretionary spending, it is likely that Mr. Ryan will be the player under the most pressure to back away from his previous conservative positions in order to form a bipartisan agreement.
Mr. Ryan, who declined to be interviewed, was largely silent during the campaign about his call for changes to the Medicare system and for vast cuts to government services, as outlined in his House budget. But his distaste for Mr. Obama's fiscal theories was unambiguous. At the Republican convention, for example, he called the Obama administration's economic vision "a dull, adventureless journey from one entitlement to the next, a government-planned life, a country where everything is free but us."
With his new muscle and increased respect from his colleagues, Mr. Ryan could conceivably scuttle any deal if he loudly opposes a solution that the speaker and the top Republican leaders embrace. But his conservative base might rebel against him if he were to endorse any deal seen as awarding too much to Mr. Obama and the Democrats, particularly on tax rates. Some Republicans think the pitfalls are dangerous enough that Mr. Ryan might consider leaving Congress altogether to work on his policy agenda without the inherent headaches of the Hill.
"He has to think about what he wants his role to be," said Representative Tom Cole of Oklahoma. "Is he going to run in 2016, or run for something else in Wisconsin, or play a bigger role in the House? He's going to play an outsize role here because of the national profile he now has, but on the other hand, this conference is quite happy to act independently."
Not all Republicans are quite so charmed by Mr. Ryan. He has engendered some exasperation among appropriators and other members who have been forced to apply his stringent budget numbers to their spending bills. Further, in the first test of his postelection influence, Mr. Ryan aggressively supported two conservative candidates for House leadership roles who failed in their bids.
For all the attention it attracted during the campaign, the Ryan budget, unlike other types of legislation, is a nonbinding agreement that does not go through the rigors of a conference committee.
Mr. Ryan has returned to the Hill voicing support for Mr. Boehner, a departure from last year, when he was wary of bipartisan deficit solutions, including the one Mr. Boehner tried to negotiate with the president.
"Speaker Boehner has outlined a bipartisan way forward to avoid the 'fiscal cliff' and get our economy growing," said Conor Sweeney, Mr. Ryan's spokesman, "with common-sense entitlement reform coupled with pro-growth tax reform. We can find common ground on responsible spending restraint and greater revenue through economic growth, but we have yet to see either a serious plan or leadership from President Obama."
Democrats, who recognize Mr. Ryan's ability to pull his fellow Republicans into a deal, are also skeptical of his role.
"I find it very fascinating," said Senator Patty Murray, a Democrat from Washington State who will become the Senate Budget Committee chairwoman, "because his vision was actually on the ballot and Americans decided to go in a different direction."
While Ms. Murray noted that Mr. Boehner was the official leader of the House Republicans and that she found the speaker's recent conciliatory tone "encouraging," she said Mr. Ryan's impact was a wild card. "If he is bringing Ryan in to have his budget of the past as the present stance," she said, "it is going to be long row to hoe. If they are bringing Ryan in to listen and compromise, that will represent a path forward."
Mr. Ryan, who was as shocked by his ticket's loss as Mitt Romney was, spent the morning after the election in a Boston hotel eating breakfast with his family and ruminating about what they had been through, his brother Tobin Ryan said.
Contrary to his fear that a campaign would wear him down, aides said, Mr. Ryan was invigorated by the race. He particularly enjoyed his time spent in Iowa, where his wife, Janna, visited her grandmother's home for the first time in many years.
"There was certainly a little bit of a fog immediately after," Tobin Ryan said. "We shared our thoughts, and I think as a family it made us even closer."
That day, Mr. Boehner called Mr. Ryan to go over the statement the speaker would make later that day on Capitol Hill, signaling a softened approach to a budget deal. Three of Mr. Boehner's aides who served on Mr. Ryan's campaign made their way back to town.
Mr. Ryan, joined by his two brothers, then went pheasant hunting, dropping so far out of the news cycle that he was only vaguely aware of the controversy brewing over the attack on the American mission in Benghazi, Libya. "There is no better medicine for Paul," Tobin Ryan said, "than getting out in the fresh air and water with dogs looking for some birds."
When Mr. Ryan returned to Capitol Hill last week, he was met with a standing ovation from his Republican colleagues, a bear hug from Mr. Boehner and the hope from conservatives that he would hold the line on taxes and other spending.
"I hope he's front and center in this debate," said Representative Jim Jordan of Ohio, who is the departing chairman of the conservative Republican Study Committee. "He's probably our best spokesperson for how serious this debt situation is."
According to aides and others close to Mr. Ryan, he is as focused on doing the job before him as he was on winning the vice-presidential race. "We just sort of picked ourselves back up, and we are all back into our lives and jobs," Tobin Ryan said. "And frankly, I see Paul doing the same thing."
This article originally appeared in The New York Times.