(WASHINGTON) -- Three weeks after President Joe Biden's fumbled first debate, some of the delegates who pledged to nominate him at the party convention in August have now joined big-dollar donors in the push to consider other names for the top of the ticket, sources tell ABC News. And as the Democratic National Committee forges forward with plans to nominate Biden by virtual roll call weeks before the convention, they're trying to hit the brakes.
Biden's struggles are bubbling back up after they drifted to the background following the failed attempt to assassinate former President Donald Trump last weekend. Biden is now facing a critical point in his reelection bid as Democratic calls for him to exit the 2024 race continue to mount.
Last Saturday, Senate Democratic Leader Chuck Schumer had a blunt conversation with Biden, making the case it would be best if Biden dropped out of the 2024 presidential race, sources told ABC News. Nearly a week later, there are mounting calls from congressional Democrats for him to exit the race.
There have been growing concerns from donors about Biden's candidacy. Also, a handful of delegates both want Biden removed from the top of the ticket and oppose a virtual roll call, sources familiar tell ABC News.
In recent days, grassroots efforts by some worried delegates to prevent a virtual nomination have picked up steam, said Chris Dempsey, a leader of one delegate group involved.
A Democratic National Convention delegate closely involved with the push to delay the virtual roll call described informal, energetic donors, delegates and advocates who have come together to stop a president nearly all of its members believe has had a wonderful first term.
"It's very ad hoc," said the delegate, who estimated that they had joined 10 Zoom calls with between 80 and 120 people concerned about the president's candidacy since the debate. "You know, it's one individual, we'll call other individuals, and then they'll put out the word to their network. It's incredibly grassroots."
One new group that has emerged from this informal coordination is Pass The Torch, which describes itself as "a network of Democratic activists, organizers and voters" advocating to "urge President Biden to pass the torch to a new ticket that has a better chance of beating Donald Trump."
In a press release earlier this week, Pass the Torch steering committee member Aaron Regenburg -- a progressive activist and former Rhode Island state representative -- called for the DNC Rules Committee to alter its plans for a virtual roll call. The DNC has indicated that the virtual roll call has long been part of their plans -- since the party took action in rectifying a ballot certification issue earlier this spring.
"It's hard to imagine any move with as much potential to tear the Democratic Party apart as the DNC ramming through an unprecedented early nomination of Biden," wrote Pass the Torch in the release.
The DNC initially made the move to a virtual role call due to an early deadline in the state of Ohio requiring the party to submit its nominee before the convention. That deadline has since been moved, but, due to another complication with state law, the DNC has argued that nominating after the convention could put the party's ballot access at risk.
"We certainly aren't going to tempt fate by inviting challenges to policing the Democratic ticket on the ballot throughout this country," said DNC Chair Jaime Harrison in a meeting Friday.
Pass The Torch and some experts dispute that the move is legally necessary.
At a meeting on Friday, the DNC Rules Committee chairs said they do not plan to open voting until Aug. 1, at the earliest
Another newly formed grassroots group, Delegates Are Democracy, also opposes the virtual roll call vote, though the group is not calling for Biden to step aside.
"Delegates Are Democracy thinks our Party's nominee will be in the strongest position to beat Trump if the Convention follows regular order and the roll call is in-person at the Convention," wrote Dempsey, a DNC delegate from Massachusetts leading the group, in a statement. "It's important that the process be seen as legitimate and not rushed."
According to Dempsey, Delegates Are Democracy seeks to inform delegates about their rights and responsibilities in the event that Biden steps aside, initially focusing on outreach to delegates in Massachusetts, Maryland and Colorado. And Dempsey says its affiliates have had "positive and receptive" conversations with multiple Democratic House members -- though it's not yet clear if those members have plans to directly aid the group's efforts.
"We think it's essential that delegates themselves, and really all stakeholders, are reminded of the important role that they play in the democratic process," Dempsey said. "While conventions in recent years and decades have been really seen as just sort of a party or a coronation, in fact, the rules still state that delegates have the ability to decide and choose a nominee."
The Biden campaign declined a request for comment and a spokesperson for the Democratic National Committee did not comment on the delegates' efforts.
Though Democratic delegates are pledged to a particular candidate and expected to reflect the views of those who elected them "in all good conscience," according to party rules, nothing formally prevents them from voting for a different candidate during the roll call nomination vote.
Over the last two weeks, some delegates said the Biden team has made efforts to keep that from happening.
Several delegates who spoke with ABC News said they had received calls from staffers asking whether they still support Biden. Others said they had received calls merely reminding them of information about the convention and their role.
A delegate, who spoke to ABC News on the condition of anonymity and is working to coordinate opposition to Biden's candidacy, said they recently attended a webinar hosted by Biden campaign manager Julie Chavez Rodriguez, which they described as "devoid of reality."
"You would never know that we had had a bad debate and that people are asking the president to speak. Everything was rainbows, sunshines and unicorns," the delegate said. "It was completely devoid of reality. I mean, there was no mention of the elephant in the room."
Instead, they continued, Chavez Rodriguez spoke about "abortion, the AAPI community, grassroots activity, some records, some new accomplishments of the administration."
A read-out of the meeting mentioned those topics several times -- but not the debate or Biden's recent struggles.
"Communication with delegations is a routine part of convention operations," a DNC spokesperson wrote in a statement. "The Democratic National Convention Committee has been engaging regularly with state parties and their delegations in a variety of ways beginning in 2023."
The disillusioned delegates join major Democratic donors similarly unmoved by the campaign's overtures, according to longtime big-dollar donor Scott Wallace. Several major donors have called on Biden to step aside since his debate performance.
"[The campaign is] hoping to calm people down and persuade us and bring us back, and I think maybe a few have been persuaded," Wallace said.
But, he stressed, only a few.
"The overwhelming consensus is that people don't want to give to the Biden campaign, but they do want to help hold the Senate and take the House," said Wallace. "I've conveyed that to the Biden team myself and the DNC, that I'll be concentrating elsewhere as long as Biden is the candidate."
Wallace told ABC News that he has been in touch with other donors since the debate through shared donor collaboratives, 90% of whom he estimated favor Biden stepping aside.
The DNC Rules Committee will meet next week to vote on whether to nominate by virtual roll call.
ABC News' Oren Oppenheim and Jacob Steinberg contributed to this report.