Democratic presidential candidate former Vice President Joe Biden addresses the crowd during a South Carolina campaign launch party on February 11, 2020 in Columbia, South Carolina.

As former Vice President Joe Biden enjoys big new presidential campaign endorsements from a political rival and his popular old boss, he also is facing an accusation by a woman who says he sexually assaulted her 27 years ago.

Tara Reade first made her claims in a podcast last month. She recently made an official complaint to police in Washington, D.C.

Biden's campaign strongly denies Reade's accusation, telling NBC News that it "absolutely did not happen."

Deputy campaign manager Kate Bedingfield told NBC in a statement, "He firmly believes that women have a right to be heard — and heard respectfully."

"Such claims should also be diligently reviewed by an independent press. What is clear about this claim: it is untrue," Bedinfield said.

The campaign had no immediate additional comment to CNBC on Tuesday.

Read NBC News' story on the sex assault allegation against Joe Biden here

In her complaint, Reade said she was serving as an aide to then-Sen. Biden in the spring of 1993. She told police in her recent complaint that Biden used his fingers to penetrate her after she gave him a gym bag.

Reade's accusation against Biden has gained attention at a time when the former longtime senator from Delaware was preparing to fully pivot to face President Donald Trump in the election this fall.

Trump won the White House in 2016 despite the bombshell disclosure of an old "Access Hollywood" tape that revealed how he had bragged about groping women's genitals without their consent. The tape came to light weeks before the election.