U.S. Sen. Elizabeth Warren, a liberal firebrand who has taken on Wall Street and traded barbs with Donald Trump, on Monday became the most prominent Democrat to announce a challenge to the Republican president in 2020.

Warren said she had formed an exploratory committee, which will allow her to begin raising money to compete in what is expected to be a crowded Democratic primary field before the November 2020 presidential election.

She said on Twitter she would announce her decision on whether to run early in 2019.

Warren, 69, a senator from Massachusetts since 2013, became one of Trump’s fiercest critics during the 2016 presidential race and they have continued to exchange biting insults during his presidency. Trump mockingly refers to her as “Pocahontas” because of her claim to Native American ancestry.

Warren has denounced Trump as an “insecure money grubber” with a platform of “racism, sexism and xenophobia,” while Trump has described the former Harvard Law School professor as “goofy” and a “lowlife” with “a nasty mouth.”

Several hours after the announcement, Trump had not responded but Republican National Committee Chairwoman Ronna McDaniel said on Twitter that Warren was “another extreme far-left obstructionist and a total fraud.”

On Monday, Warren released a video in which she outlines her vision of a path to opportunity for all Americans, not just the wealthy.

“America’s middle class is under attack,” she says on the video. “How did we get here? Billionaires and big corporations decided they wanted more of the pie and they enlisted politicians to cut them a fatter slice.”

Warren is likely to face a crowded field of Democrats, including Sens.Kamala Harris, Corey Booker and Kirsten Gillibrand, as well as former Vice President Joe Biden. Former San Antonio Mayor Julian Castro, President Barack Obama’s housing secretary, formed an exploratory committee this month.

In searching for a candidate to run against Trump, Democrats will grapple with the tension between the party’s establishment and progressive wings that flared during the 2016 primary with Clinton and Sen. Bernie Sanders, an independent who ran under the Democratic banner.

A Warren candidacy can expect opposition from Wall Street. In the U.S. Senate, she has been a strong voice on financial issues and a self-described defender of the ordinary American against powerful interests.

Following the 2007-2009 global financial crisis, Warren emerged as a leading critic of Wall Street and continues to advocate for stiffer regulation and oversight, including reinstating a rule that would separate banks’ retail business from their riskier investment banking activities.

Warren, a member of the Senate Banking Committee, has fought the Trump administration’s efforts to weaken post-crisis financial rules, going as far as to attack moderate Democrats who backed a May rewrite of the 2010 Dodd-Frank reform law.

In a September interview marking 10 years since the financial crisis, Warren was asked about breaking up big banks. “Oh yeah,” she told the New York Times. “Give me a chance.”

She also has opposed the administration’s efforts to undermine the Consumer Financial Protection Bureau, an agency she helped create, and has pressurized the Federal Reserve to take a tough line on scandal-hit lender Wells Fargo.

Many of Warren’s policy positions have focused on economic inequality. She recently offered legislation calling on the U.S. government to manufacture generic drugs to reduce their cost. In 2017 she joined other senators in a proposal to extend the federal Medicare health insurance program for seniors to include everyone.

Warren will have plenty of competition from women driving the Democratic Party’s resurgence as well as liberals and progressives, University of Virginia professor Larry Sabato said.

Her 80 percent name recognition does not translate into actual support. “Some Democrats swear by her and love her blunt style, while others are put off by her and fear she’d lose to Trump. Warren has a lot of convincing to do,” Sabato said, adding the same is true of many other Democratic contenders.

Warren said in September she would take a “hard look” at running for the Democratic nomination in 2020. In October, she released a DNA analysis she said supported her assertion that she had Native American lineage that goes back six to 10 generations.

Trump’s use of the name Pocahontas, a 17th century Native American woman associated with the British colony in Jamestown, Virginia, was aimed at drawing attention to a controversy over her heritage raised during Warren’s 2012 Senate race.

Trump’s reference has drawn criticism from some Native American groups while others criticized Warren for trying to lay claim to a tribal nation.