Sen. Kirsten Gillibrand, D-N.Y. greets patrons at Stomping Grounds Cafe in Ames, Iowa, on Saturday, Jan. 19, 2019.
Sen. Kirsten Gillibrand, D-N.Y. greets patrons at Stomping Grounds Cafe in Ames, Iowa, on Saturday, Jan. 19, 2019.

WASHINGTON - From a young gay mayor who launched his candidacy Wednesday, to high-flying female US senators and charismatic military veterans, a crowded field of Democrats jockeying to challenge Donald Trump in 2020 has already emerged – and is sure to grow.

All told it will likely be the largest and most diverse coterie of candidates ever, with the potential for dozens of current and former lawmakers, governors, mayors, and businessmen to throw their hat in the ultimate political ring.

Here are the first politicos to enter the presidential race, 21 months before the election.

Elizabeth Warren, United States senator from Massachusetts and one of the many Democrats running for president in 2020, enters the stage with San Juan Mayor Carmen Yulin Cruz Soto at the Alejandro Tapia y Rivera Theater, in San Juan, Puerto Rico, Jan
Elizabeth Warren Pledges Help During Visit to Puerto Rico
Democratic Sen. Elizabeth Warren promised to help rebuild Puerto Rico from Hurricane Maria and support laws to give the U.S. territory equal treatment and debt relief as she condemned President Donald Trump during a visit Tuesday to the island, which has become an obligatory stop for potential and presidential candidates.Warren demanded the resignation of Brock Long, administrator of the Federal Emergency Management Agency.

Elizabeth Warren

At 69, the US Senate's consumer protection champion from Massachusetts became the most high-profile Democrat to enter the race when she announced a presidential exploratory committee on December 31. Warren is on the party's left flank, and built her reputation by holding Wall Street accountable for its missteps.

Trump has already taken aim at Warren, mocking her for her proclamation of Native American heritage.

Kirsten Gillibrand

This senator from New York cut her teeth on the battle to end sexual assault, especially in the military, before the #MeToo movement gained national prominence.

The 52-year-old fierce Trump critic is making gender and women's issues a hallmark of her campaign.

FILE - Sen. Kamala Harris, D-Calif., waves to another member of the committee during a hearing on Capitol Hil in Washington, Oct. 3, 2018.
King Holiday Draws out Democratic Presidential Hopefuls
As Americans commemorate Martin Luther King Jr.'s contributions to the nation, Democratic presidential hopefuls are fanning out across the country to honor the civil rights leader.Sen. Kamala Harris, D-Calif., used the holiday to launch a presidential campaign that, if successful, would make her the first woman and the second black candidate to become president.  

Kamala Harris

The barrier-breaking senator from California who aspires to be the nation's first black female and Indian-American president announced her candidacy this week on a day honoring slain civil rights icon Martin Luther King, Jr.

The daughter of an Indian immigrant medical researcher mother and Jamaican economist father, Harris, 54, began her career as a district attorney in San Francisco before serving as California's attorney general.

Julian Castro

Former San Antonio Mayor and Housing and Urban Dev
Former San Antonio Mayor and Housing and Urban Development Secretary Julian Castro speaks during an event where he announced his decision to seek the 2020 Democratic presidential nomination, Jan. 12, 2019, in San Antonio.

A cabinet member in the Obama era and grandson of a Mexican immigrant, Castro announced his candidacy in English and Spanish on January 12 in the heat of debate on immigration and border security.

At 44, the former mayor of San Antonio, Texas hopes to become the nation's first Hispanic president.

Tulsi Gabbard

At just 37, this congresswoman from Hawaii would be the first Hindu president if elected.

A supporter of liberal Bernie Sanders in the 2016 race, military veteran Gabbard was criticized for meeting with Syrian leader Bashar al-Assad during that country's civil war, and for anti-gay positions that she has since retracted and apologized for.

FILE - Pete Buttigieg, mayor of South Bend, Indiana, talks with a reporter at Farmers Market in South Bend, Ind., Jan. 10, 2019.
Democratic Mayor Pete Buttigieg Joins 2020 Presidential Race
Democrat Pete Buttigieg, the 37-year-old mayor of South Bend, Indiana, says he's forming an exploratory committee for a 2020 presidential bid."The reality is there's no going back, and there's no such thing as 'again' in the real world.

Pete Buttigieg

Nine months younger than Gabbard is the South Bend, Indiana mayor who joined the race Wednesday, unveiling a resolutely future-looking and optimistic message to counter Trump's darker vision.

A US Navy veteran who put his mayoral duties on hold to serve in Afghanistan, Buttigieg would become the first openly gay nominee of any major party.

Richard Ojeda

This tattooed, blunt-talking retired US Army paratrooper rose to prominence last year during his unsuccessful bid for a US congressional seat deep in Trump country.

Ojeda voted for Trump in 2016 but feels the president has failed to meet his economic promises. He seeks to return the Democratic Party to its roots as a champion of working class Americans.

Andrew Yang

This 44-year-old tech entrepreneur launched his campaign with little fanfare in late 2017, warning against the dangers that automation presents to US workers.

He has advocated for a form of universal basic income as a way to reduce inequality.

John Delaney

A wealthy businessman who served three terms in Congress, Delaney was the earliest Democrat to officially launch a bid, back in July 2017. He has crisscrossed the early-voting state of Iowa seeking to boost his name recognition.

Waiting in the wings

Several big Democratic guns have yet to commit, including former vice president Joe Biden and senators Bernie Sanders, Cory Booker, Amy Klobuchar and Sherrod Brown.

Former congressman Beto O'Rourke is considering a run, as are billionaire New York ex-mayor Michael Bloomberg and Los Angeles Mayor Eric Garcetti.

Current and former governors are in the mix too: Washington's Jay Inslee, John Hickenlooper of Colorado, Steve Bullock of Montana and Virginia's Terry McAuliffe.