California Rep. Adam Schiff has become the highest-profile Democrat to call for President Joe Biden to drop his reelection bid, even as the party pushed ahead with plans for a virtual vote to formally make Biden its nominee in the first week of August.

The move to schedule the roll call, which would come weeks before the Democratic National Convention opens in Chicago on Aug 19, follows nearly 20 Democratic members of Congress calling on Biden to withdraw from the presidential race in the wake of his dismal debate performance against Republican former President Donald Trump last month.

Late in the evening on Wednesday, ABC News reported new details about Biden's private meeting over the weekend with Senate Majority Leader Chuck Schumer at his beach home in Delaware. It said Schumer told the president it would be "better for the Democratic party, and better for the country if he were to bow out.”

A Schumer spokesperson called the report "idle speculation. Leader Schumer conveyed the views of his caucus directly to President Biden on Saturday.”

Among Democrats nationwide, nearly two-thirds say Biden should step aside and let his party nominate a different candidate, according to a new AP-NORC Center for Public Affairs Research poll — sharply undercutting Biden's post-debate claim that “average Democrats” are still with him even if some “big names” are turning on him.

Biden tested positive for COVID-19 while traveling Wednesday in Las Vegas and is experiencing “mild symptoms” including “general malaise” from the infection, the White House said.

“While the choice to withdraw from the campaign is President Biden's alone, I believe it is time for him to pass the torch,” Schiff said in a statement on Wednesday. “And in doing so, secure his legacy of leadership by allowing us to defeat Donald Trump in the upcoming election.”

Schiff is a prominent Democrat on his own, and his statement will also be watched because of his proximity to Speaker Emerita Nancy Pelosi.

It was Pelosi who revived questions about Biden post-debate, when she said recently that “it's up to the president” to decide what to do — even though Biden had fully stated he had no intention of stepping aside. The former House speaker publicly supports the president, but has fielded calls from Democrats since debate night questioning what's next.

In response to Schiff's comments, the Biden campaign pointed to what it called “extensive support” for him and his reelection bid from members of Congress in key swing states, as well as from the Congressional Black and Hispanic caucuses. Biden is travelling in Nevada this week, and the campaign noted that he's been joined on the trip by “nearly a dozen” Congressional Black Caucus members.

Still, Schiff's announcement came after Schumer and House Democratic Leader Hakeem Jeffries encouraged the party to delay for a week plans to hold the virtual vote to renominate Biden, which could have taken place as soon as Sunday, according to two people familiar with the situation who spoke on the condition of anonymity to discuss private conversations.

The Democratic National Committee's rulemaking arm is set to meet on Friday to discuss how the virtual vote plans will work and to finalise them next week.

“We will not be implementing a rushed virtual voting process, though we will begin our important consideration of how a virtual voting process would work,” Bishop Leah D Daughtry and Minnesota Gov. Tim Walz, co-chairs of the rules committee for the Democratic National Convention wrote in a letter Wednesday.

The letter also said that the virtual roll call vote won't take place before Aug 1, but that the party is still committed to holding a vote before Aug 7, which had been the filing deadline to get on Ohio's presidential ballot.

The Democratic convention runs in person from Aug 19-22, but the party announced in May that it would hold an early roll call to ensure Biden would qualify for the ballot in Ohio. That state originally had an Aug 7 deadline but has since changed its rules.

The Biden campaign insists that the party must operate under Ohio's initial rules to ensure Republican lawmakers can't mount legal challenges to keep the president off the ballot.

Sen. Peter Welch, a Vermont Democrat who wrote last week that Biden should leave the race “for the good of the country," applauded the decision to move back setting a date.

“No shortcuts, no end around,” he said. "This process shouldn't be rushed.”