Tanden, chief executive of the left-leaning think tank Center for American Progress and a longtime aide to the former secretary of state and 2016 Democratic presidential nominee, has previously been an outspoken critic of Sanders and has clashed online with progressives over policy differences.
If confirmed, Tanden would be the first woman of color to head the Office of Management and Budget, the agency responsible for drawing up and implementing the federal government's spending plan. But she faces a narrow path to confirmation: Biden's announcement Monday that he planned to nominate Tanden, 50, elicited a fierce backlash from Republicans, as well as some progressives.
The fate of Tanden, as well as many of Biden's other Cabinet nominees, depends on two Senate runoffs in Georgia on Jan. 5 that will determine whether Republicans maintain their majority in the upper chamber. If Democrats win both races, they would secure a 50-50 split in the upper chamber, with Vice President-elect Kamala Harris then casting tie-breaking votes.
"Everything toxic about the corporate Democratic Party is embodied in Neera Tanden," Briahna Joy Gray, Sanders’ former national press secretary, tweeted, sharing a video of Tanden speaking against Medicare-for-all.
Sanders has not responded publicly to Biden's decision.
The two have a historically thorny relationship: During the presidential primary in 2019, Sanders wrote a fiery letter to the Center for American Progress, which Tanden led, accusing her of "maligning my staff and supporters and belittling progressive ideas."
"I worry that the corporate money CAP is receiving is inordinately and inappropriately influencing the role it is playing in the progressive movement," Sanders wrote.
The Vermont senator, a self-described democratic socialist, also criticized a video by ThinkProgress, a project of the Center for American Progress Action Fund, which accused him of changing his rhetoric on wealthy Americans after he became a millionaire in 2016.
The bad blood runs deep. In 2019, The New York Times reported that Tanden, years earlier, had punched Faiz Shakir, Sanders' 2020 campaign manager, "in the chest." The incident allegedly occurred in 2008 after Shakir, then-chief editor of ThinkProgress, questioned Clinton about the Iraq War, an issue that had plagued her presidential campaign.
Tanden told the Times that she "didn't slug him, I pushed him."
"Neera’s always been an antagonist of the progressive left," Kurt Ehrenberg, Sanders’ former longtime political strategist in New Hampshire, told Fox News. "She kind of deserves what she gets here. She has gone out of her way to denounce things like the $15 minimum wage and other tenets of the what now is widely accepted policy in the Democratic Party."
Still, other progressive Democrats, including Sen. Elizabeth Warren, D-Mass., Rep. Barbara Lee, D-Calif., and former Georgia gubernatorial candidate Stacey Abrams, lauded Biden for picking Tanden and defended her record.
"Such a great choice to lead OMB," Lee tweeted Monday. "@NeeraTanden will bring the experience and humanity urgently needed in this position. Congratulations!"
"I agree," Warren wrote, linking to a tweet from Sen. Sherrod Brown, D-Ohio, calling Tanden "smart, experienced, and qualified" to become OMB director.
Fox News' Paul Steinhauser contributed to this report