(CNN) California Sen. Dianne Feinstein, who announced earlier this week she would seek a fifth full term in 2018, is all but guaranteed to face a serious challenger next year. The question now: who can emerge from a potentially crowded field of ambitious progressives to take on the Democratic establishment favorite?

Kevin de León, the state Senate president, who CNN reported on Thursday intends to enter the race, is the early frontrunner to advance beyond June's open primary, along with Feinstein, into a one-on-one general election campaign. He was instrumental in moving a statewide single-payer health care bill through the state senate earlier this year and has been in contact with labor leaders and elected officials.

But even as de León prepares to make his move, billionaire Tom Steyer considers his next step and the wealthy activist Joe Sanberg flirts with a run, an unexpected name, though familiar to progressives, could soon join the contest.

The political journalist Ana Kasparian, co-host of The Young Turks online news show, is actively exploring a run, a source with knowledge of her plans tells CNN.

She would likely enter the fray with the support of the Justice Democrats, a grassroots liberal organization launched by Cenk Uygur, founder of The Young Turks video network and Kasparian's frequent on-air partner.

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