BOSTON (AP) — At the core of Massachusetts Sen. Elizabeth Warren's appeal is a critique of an economic system she says is rigged against the little guy.
Helping fuel that message is a voracious fundraising machine that has turned the Massachusetts Democrat into a powerhouse in her party as she looks ahead to a 2018 re-election campaign and what supporters hope is a 2020 presidential bid.
Warren started 2017 with $4.8 million in her campaign account, the biggest piggybank of any Senate Democrat facing voters next year, according to an Associated Press review of campaign finance records.
That's also $1 million more than any Democratic member of the Senate except for Democratic leader Chuck Schumer, of New York, with $10.7 million. Schumer won re-election last year.
Warren is also ahead of eight of the nine Senate Republicans running for re-election next year. Republican Sen. Bob Corker, of Tennessee, ended 2016 with $5.9 million. Sen. Bernie Sanders, an independent who caucuses with Democrats, trailed Warren with $3.8 million. Sanders also had $5.5 million in his presidential campaign account.
Key to Warren's fundraising muscle is a wide base of supporters. Warren raked in donations from virtually every state in the past two years. Nearly all her contributions came from individual supporters, with just $34,000 from political action committees and other groups.
Even in states where President Donald Trump beat Democrat Hillary Clinton by double digit margins, Warren found tiny pockets of support.
In Kentucky, the former Harvard University law professor pulled in $5,200. In Alabama, she collected $3,200. And in Tennessee, she raised $9,600 — all states where the vote exceeded 60 percent for Trump.
The totals count only contributions above $200 during the election cycle. Just 36 percent of the $5.8 million Warren raised in 2015 and 2016 crossed that threshold.
The low average donation means Warren can return to those supporters again and again before they hit the maximum of $2,700 per election cycle.
Warren also raised about $1.2 million for her PAC for a Level Playing Field during the past two years. She donated $390,000 of that to Democratic candidates and committees.
Warren's success at cultivating small donors will be crucial to the Democratic Party's White House hopes in 2020 whether Warren runs or not, according to Peter Ubertaccio, director of the Martin Institute for Law & Society at Stonehill College.
"Her people have really figured out the secret sauce," Ubertaccio said. "Anyone who wants to be the Democratic nominee in 2020 is going to have to spend a lot of time cultivating Elizabeth Warren's supporters and donors, and ultimately her."
Warren is also adept at targeted fundraising appeals.
After Senate Republicans rebuked her for reading from a letter by Coretta Scott King during last months' debate on the nomination of Jeff Sessions for attorney general, Warren sent an email to outraged backers.
The liberal group MoveOn.org said it quickly raised more than $250,000 for Warren.
Warren also started selling "Nevertheless, She Persisted" T-shirts, echoing Republican Sen. Mitch McConnell who said, "She was warned. She was given an explanation. Nevertheless, she persisted," before silencing Warren.
Contributions to Warren also spiked in the final three months of last year, when she took in $1 million, a period that included Trump's election.
Warren may also be hoping to discourage GOP challengers.
State Rep. Geoff Diehl, one of a handful of Massachusetts Republicans considering a Senate run, said Warren's cash isn't an obstacle.
"When you do the work and represent the interests of the people in the state, you can overcome whatever financial difference there may be," said Diehl, who served as the Trump campaign's Massachusetts co-chairman.
Warren has also become a fertile campaign tool for Republicans, much like the late Democratic Sen. Edward Kennedy, whose seat Warren now holds.
The National Republican Senatorial Committee has already released a series of paid digital ads linking 10 Senate Democrats up for re-election next year to Warren, highlighting how often they've voted with her.