The tension is heightened because Biden himself is saying nothing about the allegation.
Like many Americans, he has spent the past several weeks at home to prevent the spread of the coronavirus. He hasn't held a press briefing since April 2, before multiple news organisation's reported Reade's story. The public appearances he has made, such as fundraisers or events alongside prominent Democrats, have been controlled.
Some Democrats say that approach isn't working and are urging a more forceful response.
"The campaign has issued statements, but he hasn't issued any statements in his own voice," said former Democratic National Committee Chairwoman Donna Brazile. "It's not helping, it's just damaging — not only to the person who has come forward, but it's also damaging the candidate."
Lis Smith, who worked as a top strategist on former South Bend, Indiana, Mayor Pete Buttigieg's campaign, also called on the Biden campaign to speak up.
"These accusations have not been found to be credible, so it's in the Biden campaign's interest to nip this in the bud directly and do it quickly," she said.
The November contest between Biden and Trump will be the first presidential race of the #MeToo era, which has led numerous women to come forward with allegations of sexual assault.
Trump has been accused of assault and unwanted touching by numerous women, charges he denies. He was forced to apologise during the 2016 campaign after he was heard on a recording bragging about using his fame to assault women.
Women are a core constituency for Democrats, and Biden has a mixed history.
While he authored the Violence Against Women Act as a senator, he also came under heavy criticism for his handling of Anita Hill's Senate testimony in the 1990s.
Just before he launched his 2020 campaign, several women accused him of unwanted touching, behaviour for which he apologised.
Biden has pledged to pick a woman as a running mate, and the allegation has left those thought to be in contention in a tough spot.
Stacey Abrams, the former Georgia Democratic governor candidate, said "women deserve to be heard and I believe they need to be listened to, but I also believe that those allegations have to be investigated by credible sources."
"The New York Times did a deep investigation and they found that the accusation was not credible," she added. "I believe Joe Biden."
That echoed talking points issued by the Biden campaign to surrogates last week that were obtained by AP. They pointed to investigations by the New York Times, the Washington Post and AP that found no other allegation of sexual assault and no pattern of sexual misconduct.
Some Democratic donors and fundraisers say the issue has not come up in calls with party financiers. Others worry that it could be used against Biden, much as Hillary Clinton's private email server and the activities of the Clinton Foundation were wielded against her by Trump.
Some, most notably women, say they are paying close attention to the allegations, which gave them pause.
Alex Sink, a donor and former Democratic nominee for governor of Florida, said she was "not happy" to read about the allegations against Biden. While she still plans to vote for him, she was worried his campaign was too quick to categorically deny Reade's story.
"They put themselves immediately out on a limb by saying 'It didn't happen, we categorically deny it, it's not true,'" Sink said. "That's a dangerous position to be in because they aren't leaving any room for themselves."
Some female Democratic operatives expressed concerns the allegation is particularly damaging because it's an indictment of Biden's central campaign rationale: That he provides a moral counter to Trump, and that the election is a "battle for the soul of America."
"I think the stakes could not be higher for defeating Donald Trump — but at the same time, I think we have to apply a consistent standard for how we treat allegations of sexual assault, and also be clear-eyed about how Donald Trump will use these allegations in the general election campaign," said Claire Sandberg, who worked as Bernie Sanders' organising director this cycle.
The silence from the Biden campaign has given Republicans an opening on an issue that was, in 2016, far more fraught for the GOP, when Trump was asked to answer for the more than two dozen women who alleged varying levels of sexual assault and harassment from him.
The GOP argues Democrats aren't being consistent, pointing to the aggressive questioning and coverage of Supreme Court nominee Brett Kavanaugh when he faced an allegation of sexual assault.
"The left, and their media allies, has one standard for Republicans and another standard for Democrats like Joe Biden," said Steve Guest, a spokesman for the Republican National Committee. "The double standard is appalling."
Trump himself has yet to address the issue, but Donald Trump jnr has spent weeks highlighting the allegation on Twitter, as has Trump's campaign manager Brad Parscale.
Even some Trump antagonists within the GOP say the opportunity for the President and his allies is obvious.
Rick Tyler, a former spokesman for Texas Republican Senator Ted Cruz and a prominent Trump critic, noted that the coronavirus outbreak and subsequent economic crash has "ruled out any prospect that Republicans could run on great economic times."
"And so what's left? What's left is scorched earth, and that means digging up anything they can about Biden," he said. "They're trying to make Joe Biden into something that's worse than Donald Trump."
- AP
