Turns out Mike Bloomberg is exactly what Elizabeth Warren needed to break through in the 2020 Democratic primary. And he’s not just a foil for her on the campaign trail — this is something she believes in, and it shows.

Warren was quick to attack the billionaire at Wednesday’s Democratic debate in Nevada, noting his Trump-like history of calling women “fat broads” and “horse-faced lesbians.” And the Massachusetts Democrat did not relent. She went after his history on stop-and-frisk policing as New York City’s mayor. She called him out for refusing to release from nondisclosure agreements women who have accused him or his company of harassment and discrimination. Overall, it’s clear that Bloomberg is the one candidate she absolutely, positively does not want to be the Democratic nominee.

“Look, I’ll support whoever the Democratic nominee is, but understand this,” Warren said on Wednesday. “Democrats take a huge risk if we just substitute one arrogant billionaire for another.”

Here's that early Warren haymaker. "I'd like to talk about who we're running against, a billionaire who calls women fat broads and horse faced lesbians. I'm not talking about Donald Trump. I'm talking about Mayor Bloomberg." pic.twitter.com/AS9XVbTthz — Alex Thompson (@AlxThomp) February 20, 2020

Beyond the jabs on the debate stage, Warren’s disdain for Bloomberg and others like him is very real. Warren, like Bernie Sanders, isn’t just a critic of the “billionaire class,” she is a critic of a very specific type of billionaire class: those who use the advantages of an overly complex system to get ahead while everyone else falls behind.

Bloomberg made his more than $50 billion with the Bloomberg terminal, a financial computer system that costs upward of $20,000 annually and gives the Wall Street crowd a crucial edge in playing the markets and amassing their wealth. It’s the place to be for traders, analysts, and executives, and if you want to make it in finance, it’s an exclusive way in.

Warren built the Consumer Financial Protection Bureau, a government agency aimed at eliminating complexities in the financial system that make it next to impossible for American consumers to navigate many aspects of their economic lives. While she was setting up the CFPB, she’d look at loan forms and ask, “Could you please make this simpler?”

She highlighted this in a speech at an event hosted by the think tank the Roosevelt Institute in 2010, as Vox’s Ezra Klein noted in “The case for Elizabeth Warren.” The banking industry constructed a “complexity machine” to “make it all very complicated so only the experts can understand it,” she said. Types like Bloomberg helped build and perpetuate that system.

Billionaires should be worried about Warren. Bloomberg is proof of that.

As Warren’s poll numbers rose last summer and into the fall, so did the hysteria of rich businessmen worried about the prospect of her in the White House. Trump versus Warren would be the choice between “sickness and death,” one said. We don’t need someone who “vilifies successful people,” opined another. One hedge funder was brought to tears on national television over the idea of Warren winning.

As the Nevada debate showed, all these rich guys had reason to worry about Warren: She, um, really doesn’t like them. Case in point: her performance against Bloomberg.

Warren has positioned herself as a folksy figure who has a plan for everything on the 2020 campaign trail, but as the primary goes on, OG Liz is coming out. It’s the Warren who called for “blood and teeth” on the floor in her fight to get the CFPB into the Dodd-Frank financial reform. The Warren who told Wells Fargo’s CEO he should be criminally investigated. The Warren who made so many enemies not only among Republicans but also within the Obama administration that she didn’t get the directorship of the agency she’d conceived of and fought for — and who then went into the 2012 Senate race in Massachusetts and won. She’s running for president to finish what she started when she got into government: root out the corruption she sees at the heart of so many of the country’s problems.

Bloomberg is the perfect foil for Warren — and a preview of a potential Warren versus Trump

Bloomberg, predictably, took a lot of heat at the Nevada debate. He’s spent upward of $400 million on ads to catapult himself to third place in the polls nationally, and much of his messaging up to now has largely been uncontested. All the candidates took aim at the former New York City mayor, but Warren got in some of the sharpest hits.

It makes sense: Warren isn’t just incensed that inequality exists in the United States; she also understands how the systems work to propel it.

For example, footage of Bloomberg discussing the elimination of the practice of redlining, where banks discriminated against racial minorities in making loans, and its role in the financial crisis emerged earlier this month. Warren, who after the financial crisis was the head of a congressional panel overseeing the Troubled Asset Relief Program (TARP), a $700 billion bank bailout, quickly called it out.

I'm surprised that someone running for the Democratic nomination thinks the economy would be better off if we just let banks be more overtly racist. We need to confront the shameful legacy of discrimination, not lie about it like Mike Bloomberg has done. https://t.co/Lzavpie7Iy — Elizabeth Warren (@ewarren) February 13, 2020

Warren has spent much of her career as an academic and in politics fighting against moneyed interests. She’s campaigning on a sweeping anti-corruption message, and one of her signature agenda items is a wealth tax on the ultrarich. Her campaign has been selling “Billionaire Tears” mugs for months and launched a billionaire calculator for people to tabulate how much they would owe under her “ultramillionaire tax” proposal. Among the billionaires the site links to help them figure out how much they would owe is Bloomberg.

On the debate stage and in the 2020 primary, Bloomberg has emerged as a sort of proxy for Trump, even though he’s running against him: a billionaire New York businessman with a checkered record on race and gender. But Bloomberg has better credentials than Trump — he’s richer, has been more successful in business and philanthropy, and was the mayor of the country’s most populous city for 12 years. Warren’s ability to take on Bloomberg isn’t just a warning sign for their future run-ins, it’s also a warning to Trump: Warren is here for a fight, and she’s pretty good at it.