Joseph R. Biden Jr. wasn’t the main event, and he knew it.

As he trudged from one small Iowa town to the next on a cold, grim bus tour last winter, trying and failing to generate even a spark of enthusiasm for his presidential candidacy in the leadoff caucus state, he had a habit of quietly delivering his stump speech and then welcoming a more formidable closer.

“Thank you for listening,” Mr. Biden said at a campaign stop in Storm Lake last December before ceding the spotlight to Tom Vilsack, the former governor of Iowa.

“I’m going to turn this over to a guy who’s forgotten more about farm and rural policy than I know about foreign policy,” he quipped.

It was a lonely road for Joe Biden in Iowa a year ago. As his rivals enjoyed big crowds and splashy surrogates, friends of Mr. Biden’s who had retired from elected office — including Mr. Vilsack and John Kerry, the former secretary of state — suited up once more to lend their support in what looked at times like a last hurrah as Mr. Biden plummeted toward a fourth-place finish.

Yet those frosty days in Iowa have now led somewhere more glamorous: Mr. Biden’s administration, or so he hopes.

In recent weeks, Mr. Biden — now the president-elect and unquestionably the next main event in Washington — rewarded Mr. Vilsack and Mr. Kerry with nods for prominent roles, alongside others who championed Mr. Biden during the roughest stretches of the primary campaign.

The early Iowa surrogates embraced his comparatively modest pledge of a return to normalcy — and his relentless focus on the fuzzy concept of electability — when party activists in the leadoff caucus state seemed more captivated by new faces like Pete Buttigieg or the ambitious ideas of Senators Bernie Sanders and Elizabeth Warren.

One year later, Mr. Biden is again facing skepticism from activists and officials alike. This time, it is around whether the administration he is assembling reflects the racial and generational diversity of the party and the nation — something he has promised to achieve. And Mr. Biden’s elevation of Mr. Vilsack has sparked considerable backlash from progressives and from some civil rights leaders.

The expected nominations, however, are a vivid illustration of how central personal relationships are to Mr. Biden’s view of governing. Selections including his chief of staff and his nominee for secretary of state are people who have known the former vice president for decades and often bear extensive Washington credentials.

Not to mention, in some cases, extensive Iowa credentials.

For Mr. Vilsack, Mr. Kerry and other former politicians who braved the frigid expanse of Iowa before Mr. Biden’s bid caught fire with the support of Black voters in South Carolina, the possibility of a significant role in the incoming Biden administration is a vindication of their efforts during the bleakest days of the caucuses, when their alliance with Mr. Biden was viewed by other teams more as a vestige of long-ago politics than as a winning strategy.

Even Mr. Biden’s friends realized his campaign was not doing well at the time.

“When I got there, we were going door to door in a blizzard,” said State Senator Dick Harpootlian of South Carolina, joking that he had developed post-traumatic stress disorder “as a result of my experience in Iowa,” where he volunteered and where he recalled running into Biden allies like Mr. Vilsack. “Those folks that were there in Iowa and stuck with it, those are the folks who basically bought into Joe Biden,” he said. “The politics of it at that point were not particularly bright.”

None of that dampened their zeal for the task at hand. For some of his surrogates, campaigning for Mr. Biden back then meant advocacy for a man who, they believed, could defeat President Trump. It also meant a return to the campaign trail — and perhaps renewed political relevance.

Several top surrogates had run for president themselves, including Mr. Vilsack and Mr. Kerry, and their enduring support for Mr. Biden afforded them another turn in the spotlight, complete with rallies in school gyms and coaxing of voters at coffee shops. Other allies (and former candidates) like former Senators Christopher J. Dodd and Bob Kerrey were also on-hand sometimes.

They had staff members shepherding them again. They received news media requests. They hobnobbed with friends and ran into rival candidates at Des Moines hot spots.

Mr. Kerry, the 2004 Democratic nominee, joined a diverse, rotating slate of other Biden endorsers on a seven-day bus tour across Iowa 16 years after he had won the state’s caucuses.

As the tour’s headliner, Mr. Kerry’s moves and snack cravings were captured by the Biden campaign on Instagram as he attested to Mr. Biden’s foreign policy experience.

There was some occasional rust, and some anxiety, too.

At an event in Des Moines last November as he promoted his endorsement of Mr. Biden, Mr. Vilsack admitted that he “woke up at 4:30 this morning pretty nervous about this speech.”

And Mr. Kerry, on the day before the caucuses, tweeted and then deleted a profane message rebutting a news report about his own presidential ambitions — and reaffirming his support for his friend.

Mr. Vilsack in particular was viewed as an important endorsement in the state at the time. But some of Mr. Biden’s rivals, including Mr. Sanders, Ms. Warren and Mr. Buttigieg, were enjoying boosts from celebrities like Mandy Moore and young progressives like Representative Alexandria Ocasio-Cortez — which contributed to the sense that Mr. Biden, with his stable of silver-haired white men, was out of date.

“Circulating in Iowa at the time was ‘Biden’s too old,’” said Mr. Kerrey, the former senator from Nebraska who was among the friends who campaigned for Mr. Biden during the primary race. “That was the conversation that was going on — he’s yesterday’s business. He’s too moderate.”

Mr. Kerrey allowed that the Biden lineup might not have been the most dynamic.

“If you think Vilsack was boring, you should have been with me!” said Mr. Kerrey, who is in his 70s. (He did, however, bristle at the suggestion from a reporter that Mr. Biden’s supporters were not seen to be quite as youthful or hip as those of his now-vanquished opponents. “You are suffering from ageism,” he said. “I called you out. I’ve become woke!”)

As it turned out, traditionally conservative-leaning senior citizens would help propel Mr. Biden to the presidency, and he had stronger appeal in the primary campaign among Black voters than any of his rivals did.

Now on the verge of entering the White House, Mr. Biden has signaled his intent to gather his faithful squad together again with the alacrity of a coach rallying his team for one last game. This past week, he named Mr. Vilsack as his choice for agriculture secretary. He has picked Mr. Kerry for a top climate post. And Antony J. Blinken, a longtime top aide to Mr. Biden who was spotted in Iowa with him, is now his choice for secretary of state.

If Mr. Biden’s selections so far underscore his experience and his deep bench of long-lasting relationships, it is also a stark reminder of his roots in an older, whiter generation that has at times seemed at odds with the energy in the current Democratic Party.

He may not have won over youthful crowds a year ago, but he is, his team insists, committed to empowering the next generation of Democratic leaders.

At a briefing with the news media on Friday, the incoming White House press secretary, Jennifer Psaki, made a point of highlighting younger members of Mr. Biden’s team. Mr. Biden has also named a number of people of color to major cabinet positions, including helming the Pentagon and the Homeland Security Department, even as he faces intense pressure from some in his own party who believe he needs more people of color in senior positions.

Not everyone who assisted him, even in Iowa, is so far an administration choice, including Mayor Keisha Lance Bottoms of Atlanta, who joined Mr. Kerry on the bus tour.

Mr. Kerrey also said he was not on Mr. Biden’s list.

“There are a lot of people that have endorsed Joe Biden that aren’t going to be in his cabinet,” he said. “You’re talking to one.”

Thomas Kaplan contributed reporting.