For his second impeachment trial, Trump remains largely silent.

A big difference between the second and first impeachment trials of Donald J. Trump is the sound of (relative) silence.

Unlike his first Senate trial, just over a year ago, Mr. Trump has no Twitter feed to provide play-by-play commentary, amplify supporters and attack his political opponents as the proceedings unfold. He also lacks the bully pulpit of the presidency.

Instead, as the trial began on Tuesday afternoon, the former president is expected to be busy with meetings at Mar-a-Lago, his private club in Palm Beach, Fla., while sporadically watching the trial, people close to him said on Tuesday.

Even his allies were putting up only a scattered defense of him in connection to the single charge he faces for his role in inciting the violence at the Capitol on Jan. 6. Instead, most focused their comments on the decision by the Senate to hold the trial at all now that Mr. Trump has left office, casting it as an argument over constitutional principles rather than a defense of his behavior.

“The Senate is now set to spend yet another week focused on impeaching a private citizen from an office he no longer holds,” Representative Lauren Boebert, a first-term Republican from Colorado who also encouraged the protesters, wrote late Monday on Twitter. “The Left doesn’t know how to govern and is still focused on trying to blame Trump for everything.”

Sean Hannity, the Fox host and Trump adviser, spent more of his show on Monday lashing out at Democrats than explicitly defending his friend’s actions, claiming that impeachment was “like a drug” and that liberals had become addicted to it.

Over the past few days, the Twitter accounts of many Republicans who had fiercely defended Mr. Trump during his first trial had turned to other topics.

Representative Kevin McCarthy of California, the Republican leader of the House who was one of Mr. Trump’s stoutest defenders a year ago, on Tuesday blasted the three-week-old Biden administration for taking away jobs from blue-collar workers. And Mr. Trump’s former White House press secretary, Kayleigh McEnany, posted a string of tweets celebrating the Super Bowl victory of the Tampa Bay Buccaneers.