Sen. Kirsten Gillibrand (D-NY) announced on Tuesday that she will form a 2020 presidential exploratory committee, a precursor to officially seeking the Democratic nomination.

“I’m filing an exploratory committee for the president of the United States tonight," she said during a taped interview on The Late Show With Stephen Colbert.

"I'm going to run for president of the United States because as a young mom, I'm going to fight for other people's kids as hard as I would fight for my own," Gillibrand said.

Gillibrand mentioned health care, better public schools, taking on institutional racism, and "corruption and greed in Washington" as motivators and goals for her run, noting that her progressive goals cannot be accomplished without confronting those impediments.

"I know that I have the compassion, courage, and the fearless determination to get that done," she said.

Asked by Colbert if what she was doing was a formality for actually running, she said, “It’s an important first step. It’s one that I’m taking because I’m going to run.”

The senator was also asked about swearing on the campaign trail, and she said she'd try not to do so. When Colbert asked what word she'd miss the most, Gillibrand joked that it "rhymes with duck."

He proceeded to give her a corn cob for a trip to Iowa, a plane ticket to Michigan, and a button saying she announced on Colbert. Her announcement comes just months after pledging to serve out her six-year Senate term.

Using Colbert’s late-night show as the avenue to announce news is not all that uncommon among prospective candidates. In November 2018, following her easy Senate re-election, where she actually over-performed the result for the state’s House Democrats and performed well in rural pro-Trump counties, Gillibrand told Colbert that she would give serious consideration to running for president. More recently, Sen. Kamala Harris (D-CA) made an appearance on the show as part of her book tour, though she did not officially commit to running. She is widely expected to launch her bid soon.

There had been indications, prior to her Colbert appearance, that Gillibrand was launching a campaign. Just four days ago, The New York Times reported that she recruited aides from the Democratic Congressional Campaign Committee, the Democratic Senatorial Campaign Committee, and the former digital director for recently-elected California Governor Gavin Newsom. Gillibrand is also reportedly set to visit Iowa this weekend and her camp has signed a lease for office space in Troy, New York, where she lives and where the campaign will be headquartered.

The 52-year-old New York Democrat joins a broad field of candidates that will likely expand until the end of the first fundraising quarter.

On New Year’s Eve, Sen. Elizabeth Warren (D-MA) announced the formation of her exploratory committee, which was quickly followed by a trip to Iowa and more recently a New Hampshire swing. This past Friday, Rep. Tulsi Gabbard (D-HI) said on CNN that she will soon formally announce a run. She was followed Saturday by an official presidential announcement from former HUD Secretary Julian Castro. Those candidates are in addition to Rep. John Delaney (D-MD), the first declared candidate, who has been traveling in early primary states; and former West Virginia state senator and congressional candidate Richard Ojeda.

But Gillibrand—who was appointed to fill a Senate vacancy when Hillary Clinton became secretary of state in 2009—is one of the more high-profile names to enter the field, at least among progressives. Before holding office, Gillibrand was an attorney and forged a relationship with Clinton while the latter ran for Senate in 2000.

In 2006, Gillibrand defeated Republican incumbent John E. Sweeney to represent New York’s 20th congressional district, an area including Albany and Schenectady counties that traditionally leaned conservative. She easily won re-election despite questions in both campaigns about her prior legal representation of the tobacco giant Philip Morris and contributions she received from the industry. (Gillibrand voted for a number of anti-tobacco bills in that session of Congress and activists at the time saw her as an ally).

During her tenure in the House, Gillibrand was part of the Blue Dog Coalition, voting in favor of legislation that would withhold funds from sanctuary cities and opposing amnesty for undocumented immigrants. Additionally, she advertised on her website that she had a 100-percent voting record with the National Rifle Association.

For those just getting acquainted with Gillibrand in the Trump era, in which she has voted with the president’s position less than 12 percent of the time (the lowest among her colleagues), her past views may come as a surprise.

She was confronted with her ideological shift during a 60 Minutes segment last February, explaining how she went from having an “A” rating from the NRA to an “F.”

“I went down to Brooklyn to meet with families who had suffered from gun violence in their communities," Gillibrand recounted. "And you immediately experience the feeling that I couldn't have been more wrong—you know, I only had the lens of upstate New York."

She went on to say that she was “embarrassed” because she had in fact lived in New York City for a decade.

On immigration, the New York Democrat explained her shift: “I came from a district that was 98 percent white,” Gillibrand said. “We have immigrants, but not a lot of immigrants... And I just didn’t take the time to understand why these issues mattered because it wasn’t right in front of me. And that was my fault. It was something that I’m embarrassed about and I’m ashamed of."

Gillibrand’s recent Senate tenure has been defined by this forthright, confrontational approach, one that has—at times—pitted her against powerful members of her own party. In Dec. 2017, she was the first Democratic senator to call for the resignation of her colleague Sen. Al Franken (D-MN) after he was accused of sexual misconduct. After Gillibrand’s initial statement, a number of her colleagues joined in and eventually forced his ouster.

She had also recently said that President Bill Clinton should have resigned following the revelation of his affair with intern Monica Lewinsky, a statement that put her at odds with the political family she had been so closely aligned with throughout her career.

These flashpoints lent added credibility to Gillibrand’s cultivated reputation as an advocate for women and sexual-assault victims. She has pushed legislation on sexual assault in the military and on college campuses and more recently served as a lead sponsor of the Me Too Congress Act, which aimed to ease the process for victims within Congress to come forward. And prior to that, nearly as soon as she entered the Senate, Gillibrand secured hearings on "Don't Ask, Don't Tell" for the first time in 16 years.

It was her recent action against Franken that was taken especially hard by Democratic donors, whose animus could actually prove useful for Gillibrand in a 2020 Democratic primary: As a handful of mega-donors have griped about her role in torpedoing the Minnesota Democrat’s career, Gillibrand’s small-dollar contributions have spiked. She raised more than $27 million in the 2018 cycle with $8.2 million coming from online contributions, with an average donation of $20. Gillibrand has also raised millions for women candidates via her Off the Sidelines PAC, with some 50 supported candidates winning in the 2018 cycle.

She has also co-sponsored Sen. Bernie Sanders’ (I-VT) Medicare for All legislation, backed Sen. Cory Booker's (D-NJ) Marijuana Justice Act, swore off corporate PAC contributions, and said last year that the U.S. Immigration and Customs Enforcement (ICE) needs to be dismantled.

“I believe that it has become a deportation force,” she told CNN at the time. “And I think you should separate out the criminal justice from the immigration issues. And I think you should reimagine ICE under a new agency with a very different mission and take those two missions out. So we believe that we should protect families that need our help and that is not what ICE is doing today. And that’s why I believe you should get rid of it, start over, reimagine it, and build something that actually works.”