Sen. Kamala Harris Kamala HarrisThe Hill's Campaign Report: Trump and Biden vie for Minnesota | Early voting begins in four states | Blue state GOP governors back Susan Collins Kamala Harris: Black Americans have been 'disproportionately harmed' by Trump Biden town hall draws 3.3 million viewers for CNN MORE (D-Calif.) used more than $100,000 in campaign funds for Facebook ads about the launch of her 2020 campaign for president.

Ian Sams, Harris's campaign press secretary, told The Daily Beast on Thursday that Harris spent more than $100,000 on 25,000 Facebook advertisement variants around her campaign launch, almost double the amount ($52,574) spent by Sen. Elizabeth Warren Elizabeth WarrenBiden's fiscal program: What is the likely market impact? Warren, Schumer introduce plan for next president to cancel ,000 in student debt The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon MORE (D-Mass) on Facebook ads during the week of her 2020 campaign's launch earlier this month.

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Harris's campaign told the Daily Beast that the Facebook ads contributed to the California senator expanding her supporter email list by 20 percent over the course of the week, as well as a fundraising haul of more than $1.5 million.

The numbers put Harris well ahead of her announced competition in the Democratic primary in terms of fundraising, though an aide to former Housing and Urban Development Secretary Julián Castro cautioned in a statement to the Beast that the race was still early.

“We’re starting from scratch but we expect to grow exponentially as we get Castro’s message out,” Castro's aide told the Daily Beast. “We are declining all PAC money and donations from lobbyists. Don’t write us off because we didn’t raise $1.5M in a day. Our race is a marathon, not a sprint.”

Harris's announcement Monday coincided with national celebrations of Martin Luther King Jr. Day. In her announcement speech, the senator pledged to fight for average Americans against "self-interest" in government.

"Today, the day we celebrate Dr. King, is a very special day for all of us as Americans, and I'm honored to be able to make my announcement on the day that we commemorate him," she said.

"When I look at this moment in time, I know the American people deserve to have someone who is going to fight for them ... and put them in front of self-interest," Harris added.