Sen. Kirsten Gillibrand entered the growing field of 2020 Democratic presidential contenders Tuesday, telling television host Stephen Colbert that she's launching an exploratory committee.

"It's an important first step, and it's one I am taking because I am going to run," the New York senator said on The Late Show with Stephen Colbert. She listed a series of issues she'd tackle as president, including better health care for families, stronger public schools, and more accessible job training.

Gillibrand, 52, has already made plans to campaign in Iowa over the weekend, more than a year before the leadoff caucus state votes.

She joins what is expected to be a crowded primary field for the Democratic nomination that could feature more than a dozen candidates. Already, Massachusetts Sen. Elizabeth Warren has announced her own exploratory efforts, and decisions by a number of other senators are expected in the coming weeks.

Gillibrand was appointed to the U.S. Senate in 2009 to fill the seat vacated by Hillary Clinton, and was elected to the U.S. House of Representatives three years earlier for Brunswick, New York, a heavily Republican district. A congresswoman who once championed gun rights, her positions would later move to the left. She has been among the Senate's most vocal members on issues like sexual harassment, military sexual assault, equal pay for women and family leave, issues that could be central to her presidential campaign.

During her 11-minute interview with Colbert, Gillibrand mostly steered away from direct attacks on President Donald Trump, opting instead for a more positive message.

"I'm going to fight for other people's kids as hard as I would fight for my own," said Gillibrand, a mother of two sons, ages 10 and 15.

New York's junior senator also touched on schools, job training, and climate change, and she highlighted bipartisan legislation she helped get passed in the Senate, including the 9/11 health bill and the repeal of Don't Ask, Don't Tell. She also talked broadly about taking on systems of power.

"Which is taking on institutional racism. It's taking on the corruption and greed in Washington, taking on the special interests that write legislation in the dead of night," she said.

As she works to distinguish herself from likely rivals, Gillibrand will be able to draw from the more than $10.5 million left over from her 2018 re-election campaign that she can use toward a presidential run.

Gillibrand's decision to run had become increasingly clear recently despite vowing to serve her full term before she was re-elected less than three months ago. Last week came news she chose Troy, New York near her home for her campaign headquarters, and that she hired key campaign staff and was planning a trip to Iowa.

Her campaign website went live Tuesday night, and she is slated to appear at a diner in Troy on Wednesday as she begins trying to define and distinguish herself in a growing field that already includes Warren and former Housing Secretary Julian Castro.

"I have the compassion, the courage, and the fearless determination to get that done," the New York senator said.

Information from the Associated Press was used in this story.