Activist groups are hopeful that their views will get a hearing from Yellen, but there are key areas -- pandemic relief, trade, financial regulations. student loan debt -- where she could quickly disappoint them, based on her record.

While she's a strong advocate for a big new economic relief package, she has also spoken forcefully about the need to get the growth of the federal deficit under control. She is a long-time supporter of free trade, which many progressives consider a threat to American workers.

And while she oversaw the imposition of tough new banking rules as Federal Reserve chair in the Obama era, she played little direct role in shaping them, raising questions about how aggressive she'd be about new financial regulations.