As former President Donald J. Trump goes on trial on Monday in Manhattan, President Biden and his allies are not likely to say much.

For Democrats, a former president facing criminal charges over covering up a sex scandal surrounding the 2016 campaign speaks for itself. The media coverage will be constant, especially if Mr. Trump takes the stand, which he has floated as a possibility. And while Mr. Trump faces up to eight weeks in court, Mr. Biden will be on the campaign trail and employing a “Rose Garden strategy” as he governs from the White House, a contrast that the president’s aides hope voters will view favorably.

The approach could be bolstered by the fact that Mr. Trump will be appearing in a court case involving salacious details and questionable financial maneuverings while Mr. Biden is addressing a conflict in the Middle East.

Mr. Biden and his campaign have said nothing publicly about the criminal indictments against Mr. Trump, worried about improperly influencing the cases or stoking Mr. Trump’s repeated allegations — made without evidence — that Mr. Biden has engineered the charges.

Many of the deep-pocketed outside Democratic groups supporting the Biden campaign are charting a similar path. Part of their calculation, they say, is that ads promoting Mr. Biden’s record or arguing that Mr. Trump is a threat to democracy are testing better with voters than highlighting Mr. Trump’s legal troubles. Another consideration is that the Manhattan case, which is being brought by the Manhattan district attorney, Alvin Bragg, is not easily explained in a sound bite or a 30-second ad.

“I just don’t think in the end it’s the strongest argument for voters,” said Steve Schale, a Democratic strategist running a pro-Biden super PAC called Unite the Country. “Campaigns have limited resources and you spend those resources in a way that moves the most votes.”

Mr. Schale’s group is planning to spend roughly $40 million later this spring on an ad campaign in Michigan, Pennsylvania and Wisconsin focused on Mr. Biden’s accomplishments and attacking Mr. Trump for being anti-democratic.

The Biden campaign declined to comment on its strategy and the main pro-Biden super PAC, Future Forward, did not respond to a request for comment. Nor did a spokesman for Mr. Trump’s campaign.

When Mr. Trump goes on trial on Monday, he will be the first U.S. president to face criminal prosecution. He stands accused of falsifying business records to conceal a hush-money payment to Stormy Daniels, the former adult film star, as part of an effort to influence the 2016 election. The case is one of four criminal indictments he faces, although it may be the only one that reaches trial before Election Day. Mr. Trump has denied guilt in them all.

“Two days from now, the entire world will witness the commencement of the very first Biden trial,” Mr. Trump said at a rally in eastern Pennsylvania on Saturday night, baselessly implying that the president had engineered the charges.

The other argument for the Biden campaign and affiliated groups to focus elsewhere is that there doesn’t appear to be much voter interest in the proceedings. A New York Times/Siena College poll found that just one-quarter of voters said they were paying “a lot” of attention to the Manhattan case. Other polls have shown that voters consider this case the least serious of the indictments against Mr. Trump.

That said, Democratic groups certainly won’t ignore the trial. Those that specialize in “rapid response” communications plan to monitor Mr. Trump’s behavior in court and at his frequent post-court news conferences and deliver their messages on social media.

“Whenever we see Trump in court, he’s one of the worst and most undisciplined versions of himself,” said Brandon Weathersby, a spokesman for the liberal opposition research group American Bridge. “He’s combative with the judges, prosecutors, members of the press. He’ll toss out rants on social media during court proceedings. And so for us, we think that our job in all of this is to highlight those moments for voters to kind of cut through the noise.”

Meanwhile, as Mr. Trump sits in court this week, Mr. Biden will campaign in his hometown, Scranton, Pa., on Tuesday, with stops in Pittsburgh on Wednesday and Philadelphia on Thursday. That is the kind of split screen that Democrats believe will favor them.

There is, of course, no guarantee that Mr. Biden won’t be tempted into popping off about the trial as he interacts with voters and the news media. The president has never been viewed as the most disciplined campaigner.

And Democrats could change their calculations about the wisdom of highlighting Mr. Trump’s legal troubles if he should be convicted in the Manhattan case. Some polling shows that swing-state voters could be moved if Mr. Trump heads into Election Day as a felon.

The federal election interference case against Mr. Trump over his efforts to retain power, known as the Jan. 6 case, could also shift how Democrats approach the issue, if it goes to trial. That case is seen as the most directly illustrative of the Democratic argument that Mr. Trump is a threat to democracy.

But for now, many Democrats believe the frequent presence of Mr. Trump in a Manhattan courtroom will do their work for them.

“The Republican Party right now is led by the most extreme members of the party and they’re led by Donald Trump,” said Representative Suzan DelBene, of Washington, the head of the campaign arm of the House Democrats. “The trial reinforces the extremism and who’s in charge of the Republican Party right now.”

Lisa Lerer, Ruth Igielnik and Michael Gold contributed reporting.