WASHINGTON — Senator Elizabeth Warren on Friday urged President Obama to appoint Janet Yellen to head the Federal Reserve, choosing to back Yellen instead of her former Harvard colleague, Larry Summers.

The influential Massachusetts Democrat signed onto a one-page letter circulating among Senate Democrats that calls on Obama to appoint Yellen, who would become the first woman to hold the position. Yellen is currently the Fed’s vice chair, and has worked closely with Chairman Ben Bernanke, who is expected to retire when his term ends in January.

Speculation has swirled in Washington this week that the position is down to two front-runners, Yellen and Summers.


Summers is a former top Obama administration adviser who was also treasury secretary under President Clinton. But he is also a voluble presence, known for a tough management style.

Senate Democrats have been circulating a letter that doesn’t mention Summers, but makes a point of praising Yellen — and urging the president to appoint her. The letter has not been made public, and a copy obtained by the Globe did not list signatures. One source estimated that nearly half of the Senate Democrats had signed on.

A Warren spokeswoman confirmed to the Globe late on Friday that the Massachusetts senator had signed it. The state’s other senator, Democrat Edward J. Markey, had not signed, according to his office.

Warren and Summers have a history that has been at times cordial, and at times contentious.

Warren was a professor at Harvard Law School when Summers resigned as Harvard’s president in 2006 for making comments suggesting that gender differences partly explained why fewer women pursued careers in math and science.

They later clashed when Warren was heading a congressional oversight panel. In interviews, Warren said that her views differed sharply from those of Summers, as well as then-Treasury Secretary Timothy Geithner. They were too supportive of the big banks, she suggested, while she stuck up for everyday Americans.


“I think we have different world views,’’ she told PBS’ Charlie Rose in 2010.

“I think that Summers and Geithner are smart,’’ she added. “I think they`re honorable. I think they approach the economy and the world through the largest institutions. And they see the world from a top-down perspective. I spent 25 years somewhere else.’’

Beyond confirming that she had signed the letter, Warren’s office declined to comment further. A spokeswoman for Summers declined to comment.

Warren was asked earlier this month who she wanted to replace Bernanke. She initially named Paul Volcker, who has held the position before and is unlikely to return (’’I love Paul Volcker,’’ she said. “I think he’s terrific.’’)

When asked about Yellen and Summers specifically, Warren said, “Two very smart people. In that sense, we’re really lucky. We’ve got really smart, talented people who can serve in that position.’’

But when asked if Summers could get confirmation in the Senate, she replied, “I don’t know.’’