The field of Democratic candidates to contest Donald Trump in 2020's presidential election has grown larger as Kamala Harris has officially launched her campaign.

Harris, a first-term senator for California who previously served as the state's attorney general, announced her campaign on ABC's Good Morning America and also released a video on social media with the caption "I'm running for president. Let's do this together."

Harris' announcement coincides with Martin Luther King Jr. Day. If Harris is eventually able to win the Democratic nomination, she would be the first African American woman to be a party nominee in the presidential election.

Throughout her tenure as a public servant, Harris has solidified herself as an  effective defender of immigrants, the LGBTQ community and people of color. Harris also defended Obamacare and made some progress in police reform. However, an inconsistent track record on certain issues has led some political commentators to wonder whether she is progressive enough for a political climate that does not favor centrism.

"Time after time, when progressives urged her to embrace criminal justice reforms as a district attorney and then the state's attorney general, Ms. Harris opposed them or stayed silent," wrote law professor Lara Balezon in the New York Times.

Harris joins Elizabeth Warren and Kirsten Gillibrand in a field of nominees that will inevitably continue to grow. Cory Booker, Sherrod Brown, Amy Klobuchar and Bernie Sanders are reportedly also weighing presidential bids.