Washington (CNN) Kamala Harris just picked up her biggest endorsement to date in her fledgling 2020 campaign: Congresswoman Barbara Lee, former Congressional Black Caucus chair and all-around anti-war and social justice activist star.

Lee, who has been called "the House's lefty conscience" will be California co-chair of Harris' presidential campaign.

"Watching Kamala's career in the East Bay and San Francisco for 20 years, I've witnessed her deep passion for justice and opportunity and I know she will be a president truly of the people, by the people, and for the people," Lee said in a statement obtained exclusively by CNN.

"She will increase working Americans' incomes, expand health insurance to more Americans and restore dignity and responsibility to the Oval Office. She is a leader uniquely qualified to bring us together and mobilize a movement of Americans to return power to the people."

For Harris, who is set to go to South Carolina this weekend , it is an undeniable boost. While there is all sorts of data that suggests endorsements don't really move voters, for Harris, Lee's endorsement helps her burnish her progressive credentials and adds to her California show of force -- and 400 delegates will be up for grabs in Harris' home state on Super Tuesday.