He has a new, carefully groomed beard. He bantered with bros for hours on an irreverent comedy podcast. And on Tuesday, he criticized the Trump administration through an appeal to patriotism in a state early on the presidential nominating calendar.

Pete Buttigieg is inching back into the Democrats’ spotlight this spring with a series of appearances that have prompted speculation about how one of the party’s most evidently ambitious politicians might spend the lead-up to 2028.

With Democrats still searching for a direction and a standard-bearer after November’s loss to President Trump, supporters of Mr. Buttigieg, a smooth-talking former mayor from Indiana who served as the transportation secretary in the Biden administration, hope he might take up that mantle.

Without ever uttering Mr. Trump’s name, Mr. Buttigieg, in front of a veteran-heavy crowd of more than 1,600 in Cedar Rapids, Iowa, assailed the president’s efforts to cut the Department of Veterans Affairs and his broader handling of the country. He implored attendees to exert “peaceful but energetic” pressure on their representatives to block cuts to federal agencies and tax breaks for the wealthy. And he expressed optimism that people would resist Mr. Trump and restore faith in democracy.

“There is a parade of horribles emanating from this White House,” said Mr. Buttigieg, 43. But, he added, “the American people bow to no king.”

Mr. Buttigieg’s town hall in Iowa, sponsored by VoteVets, a progressive veterans group, was his most notable involvement yet in the Democratic shadow primary race, with prominent governors and members of Congress competing for attention as they weigh 2028 presidential bids.

They have been busy: Gov. Tim Walz of Minnesota, the party’s 2024 vice-presidential nominee, held a town hall in Iowa in March and plans to attend state party conventions this month in California and South Carolina, which is expected to host an early primary. Gov. JB Pritzker of Illinois ramped up 2028 speculation with a fiery speech last month in New Hampshire, another state traditionally at the front of the primary calendar. Senator Ruben Gallego of Arizona held an event last week in Pennsylvania, a top battleground state.

And Representative Alexandria Ocasio-Cortez of New York, who has been less obvious about 2028 signaling but is seen as a possible contender, has been traveling the country alongside Senator Bernie Sanders of Vermont to rally supporters against the influence of big money in politics.

VoteVets is an ally of Mr. Buttigieg, a former Naval intelligence officer who deployed to Afghanistan, but the group is also close with other potential 2028 contenders with military experience, including Mr. Walz and Mr. Gallego.

Mr. Buttigieg, for his part, has shown particular interest in how Democrats can win back the overlapping mix of working-class voters, men and disenchanted Americans who gravitated to Mr. Trump’s vision of upending the establishment last November.

At the town hall in Iowa, he offered no hints as to his ultimate political aspirations, though he did remind attendees of his past success in the Hawkeye State.

During one previous trip, “I was sort of winning the Iowa caucus,” he said casually, scratching his head as though reluctant to brag. “Run again!” someone yelled from the crowd. Mr. Buttigieg just chuckled.

Whether Mr. Buttigieg can successfully reach beyond the highly engaged voters who tune into MSNBC and read traditional news — the people who would attend a midweek political event in a non-election year — could determine whether he stands out in what is expected to be a crowded primary field.

Mr. Buttigieg has been explicit about his goal of reaching the apolitical voters who have said they feel the Democratic Party has become too focused on elites. Fielding questions from attendees on Tuesday about how the party could regain voters’ trust, he suggested it needed to have “some tough conversations.”

Democrats, Mr. Buttigieg said, must devise more proactive policy plans, rather than just defining themselves in opposition to Mr. Trump. And the party needed to “connect everything we believe, everything we say, everything we do, to everyday life,” he said.

Mr. Buttigieg also acknowledged his party had done a poor job last year by insisting that the economy was doing well by traditional metrics even as voters were consistently expressing financial frustration, comparing it to minimizing the angst of an angry spouse. “How does that go over?” he asked.

Speaking with reporters after the event, Mr. Buttigieg was less definitive about whether Democrats had erred in supporting President Joseph R. Biden Jr. in the re-election bid that he ultimately abandoned over concerns about his age.

Asked whether he had seen Mr. Biden experience cognitive decline last year — something Mr. Biden has pushed back against in recent interviews — Mr. Buttigieg did not answer directly. He did say that when he and Mr. Biden dealt with a bridge collapse in Baltimore last spring, “the same president that the world saw addressing that was the president that I was in the Oval with.”

Would the party have been better off if Mr. Biden had not run for re-election?

“Maybe,” Mr. Buttigieg allowed. “Right now, with the benefit of hindsight, I think most people would agree that that’s the case.”

Zach Wahls, a Democratic state senator in Iowa who is considering a run for U.S. Senate, said Mr. Buttigieg was “trying to meet voters where they are, and I think that is one of the most important things for the Democratic Party to do going forward.”

“His ability to communicate in an authentic, in-depth way is what really gets through to people who may not otherwise be superpolitical or who are frustrated with both parties,” Mr. Wahls added.

That was a sentiment echoed by attendees on Tuesday, who said they appreciated Mr. Buttigieg’s straightforward way of speaking.

“He doesn’t talk that political speech,” said Chris Bzdill, 55, of Cedar Rapids. “He understands that not everybody may agree with his view, but he’s going to give people an idea of where he stands. He’s not going to sit on the fence.”

The Iowa Republican Party had a different perspective on Mr. Buttigieg’s event. In a statement, it said Mr. Trump was improving access to health care for veterans while cutting wasteful spending at the Department of Veterans Affairs, and offered a contrasting take on Democrats from local veterans themselves.

“Mayor Buttigieg and Democrats want to rewrite history, but veterans across Iowa know the truth: President Trump put them first,” Wayne Kreutner, an Air Force veteran in the Cedar Rapids area, said in the statement. “Joe Biden and the Democrats put politics first.”

Mr. Buttigieg first burst onto the national scene in the 2020 Democratic presidential primary as the little-known mayor of South Bend, Ind., population 100,000. He quickly gained acclaim for his sharp debate lines and cogent communication skills, but ultimately faded as Mr. Biden consolidated his support.

Lately, Mr. Buttigieg has been more visible, addressing college students at the University of California, Santa Barbara; getting laughs with Stephen Colbert on his late-night show; and appearing on the “Flagrant” comedy podcast, which bills itself as delivering “unruly hot takes” and opposing political correctness.

Mr. Buttigieg, who now lives in Michigan with his husband and two children, was considered a contender for the open Senate and governor races there, but he bowed out of both contests in March, fueling more speculation about a presidential run.

Mr. Wahls, a friend of Mr. Buttigieg’s who attended the town hall, said before the event that he was eager to see Mr. Buttigieg’s new beard in person. “Beard looks good!” he wrote in a text.

But did he think it could be some sort of careful political calculation, planned to better appeal to the everyman voter? “I don’t know,” Mr. Wahls replied. “Every man’s relationship with his facial hair is a little different; I won’t speculate.”