Sen. Elizabeth Warren (D-MA) is putting her significant influence and fundraising prowess behind California Attorney General Kamala Harris in the race to replace retiring Sen. Barbara Boxer (D-CA).

“California Attorney General Kamala Harris is a smart, tough, and experienced prosecutor who has consistently stood up to Wall Street,” Warren said in an email to supporters that asked for donations to support Harris’s campaign. “I worked with Kamala, and I saw up close and personal that she is tough, she is principled, and she fights hard.”

Harris announced earlier this week that she would run to succeed Boxer, instantly making her a frontrunner in the race. Billionaire enviromentalist Tom Steyer and Rep. Loretta Sanchez (D-CA) are two other prominent names who are considering a campaign.