Amid Uncertainty, Biden Campaign Tries to Keep Control of Delegates

President Biden’s campaign continued reaching out to Democratic convention delegates on Thursday to ensure their support amid mounting concerns that his candidacy could cost the party the White House and lead to losses down the ballot.

An overwhelming majority of delegates are pledged to Mr. Biden, but a growing if still limited number of them are expressing pessimism about the party’s chances with him at the top of the ticket as his polling has lagged and his public appearances have been uneven.

Since Mr. Biden’s disastrous performance in a debate against former President Donald J. Trump last month, the Biden campaign has been calling hundreds of convention delegates to ask each if they understood their role as a “pledged Biden delegate,” according to interviews with about a dozen of them and others familiar with the calls.

Some said the campaign went further, asking if Mr. Biden could still count on their support.

Party officials and Biden campaign allies have also urged delegates to keep quiet about their concerns, according to interviews and messages obtained by The New York Times. In some cases, delegates said they felt as if expressing dissent might cost them the chance to participate in the convention.

The Biden campaign said that the calls to delegates began well before the debate and that they were part of a normal outreach process to organize thousands of people ahead of a nominating process and convention that is logistically challenging even under normal circumstances.

“Delegate calls are ongoing,” Lauren Hitt, a Biden campaign spokeswoman, said on Thursday. “The president has been clear he has no plans to drop out.”