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.