Her confirmation may hang on the outcome of Georgia's Senate runoff elections in January, which will determine which party gets control of the upper chamber.
"Like me, [Tanden] was raised by a single mother and knows firsthand the importance of having an economy that treats all people with dignity and respect," Harris tweeted Friday. "I know with her at the helm of the Office of Management and Budget, our budget will fully reflect our values."
Her tweet came in response to a video Tanden posted to Twitter in which she told how she was raised by a single mother, and how her family depended on welfare to succeed.
"Families all across our country are worried," Tanden wrote. "Worried about paying bills, rent – too many of the most basic necessities have been placed out of reach. Our government must invest in people to put an end to this worry, and revive our economy."
Biden also defended Tanden in an interview with New York Times columnist Thomas Freidman published Wednesday, suggesting that Republican criticism of his pick -- because of her "trail of nasty tweets" -- is hypocritical.
"That disqualifies almost every Republican senator and 90 percent of the [Trump] administration,” Biden said. “But by the way, she’s smart as hell. Yeah, I think they’re going to pick a couple of people just to fight [over], no matter what.”
On the flip side, Tanden has not been so quick to defend the former vice president.
In an email sent to John Podesta, former chief of staff for Bill Clinton, on Oct. 20, 2015, Tanden said she had more confidence in Hillary Clinton, who was running for president at the time, than Biden.
“The good thing about a Biden run is that he would make Hillary look so much better,” Tanden said.
If confirmed by the Senate, she would be the first Indian-American and first woman of color to serve as director of the OMB.