Maxine Waters of California is known as a partisan firebrand who gives as good as she gets, especially where President Trump is concerned.
Now, with Democrats assuming control of the House in January, the California Democrat is about to become more visible than ever before, with the power to slow down an important part of Trump's agenda and even shine a light on his company's finances.
"I will be the first African-American, the first woman, to chair the powerful Financial Services Committee," she told a crowd of supporters in Los Angeles right before the election. "That's all of Wall Street. That's all the insurance companies. That's all the banks."
The 80-year-old lawmaker from Los Angeles now serves as the committee's ranking member. There, she has positioned herself as a voice of the little people, relentlessly grilling bank regulators and executives about the impact of their policies on small businesses and homeowners.
"She is a tough and savvy defender of consumer protection and holds the feet of the banks and the Trump administration regulators to the fire," says Mike Calhoun, president of the Center for Responsible Lending.
Financial services officials say Waters knows how to work with other lawmakers and they expect her to find common ground with Republicans on some issues, such as data security and flood insurance.
"Congressman Waters is a skilled legislator, and she has devoted considerable energy to issues affecting the mortgage industry, such as affordable housing, and we look forward to continuing to work with her," says Robert Broeksmit, president of the Mortgage Bankers Association.
But Waters is also unafraid to talk back to critics, and she can be confrontational when necessary.
Earlier this year, she interrupted Treasury Secretary Steven Mnuchin during a hearing, by saying, "reclaiming my time" over and over. Video of the exchange between Mnuchin and "Auntie Maxine," as she is nicknamed, quickly went viral.
She has often heaped scorn on President Trump, deriding his morals and his policies, and has been more willing than most Democrats to openly advocate his impeachment.
Trump in turn has disparaged her as having a "low IQ," a taunt many people condemned as racist. Waters was one of a handful of Trump critics who were mailed pipe bombs last month. (None of the bombs went off.)
The threats and insults have only made her more defiant.
Waters drew criticism recently when she told supporters not to be afraid to harass Trump administration officials if they see them in public, a remark that made even some Democrats uncomfortable.
With congress divided, Waters and other Democrats are unlikely to get much legislation passed over the next two years, says Ian Katz, an analyst at Capital Alpha partners.
But as chairwoman, Waters will have the power to set the committee's agenda, hauling bank executives and regulators before the public and drawing attention to issues she cares about, he says.
"She can't pass laws. She can make bank executives and some of the regulators appointed by Trump very uncomfortable and create some awkward moments for them," Katz says.
Waters can also use the committee's power to slow down the effort by the Trump administration to deregulate banks, by writing letters to agencies such as the Federal Reserve and the Office of the Comptroller of the Currency and calling hearings, he says.
"It takes a lot of bandwidth of these agencies when they have to appear before Congress. The legal team has to get involved and prepare the head of the agency. All of this has the effect of slowing down the agency and its deregulatory work," Katz says. "She can't necessarily change what they're going to do, change the regulations, but she could slow things down."
As committee chair, Waters can also make Trump's life more difficult in another important way, by promising to raise questions about his company's financial ties to Deutsche Bank, which has been fined by regulators for money laundering.
Deutsche Bank was the only major bank willing to lend money to Trump after his string of bankruptcies at his casinos in the nineties.
"We know that Deutsche Bank is identified as one of the biggest money-laundering banks in the world perhaps, and that they're the only ones who were amenable to providing loans to this president. So we want to know some things about that," Waters told Bloomberg TV last week.
For its part, Deutsche Bank says it's ready to work with the committee.
In a statement, the bank said it "takes its legal obligations seriously and remains committed to cooperating with authorized investigations. Our recent record of cooperating with such investigations has been widely recognized by regulators. We intend to keep working in this spirit if we get an authorized request for information."