SAN ANTONIO ― Former Housing and Urban Development Secretary Julián Castro officially announced a run for the White House on Saturday, becoming one of the first fully committed candidates in what is expected to become a crowded contest for the 2020 Democratic nomination.

“So many journeys for me and my family have started right here,” Castro told a crowd at Guadalupe Plaza on San Antonio’s west side, blocks from the home where he grew up and the church where he was baptized. “Today we begin another one.”

He then rattled off a list of campaign pledges that planted him squarely within the rising progressive side of the Democratic Party. He reaffirmed his rejection of corporate PAC money and support for “Medicare for all,” called for bail reform and promised that his first executive action would be to rejoin the Paris climate accord.

“There is a crisis today,” Castro said. “It’s a crisis of leadership. President Trump has failed to uphold the values of our great nation.”

Castro, 44, has long showed signs of high political ambitions, but was not known for staking out controversial positions until he launched his presidential exploratory committee last month. Since then, he has struck a markedly more left-wing tone, and his speech Saturday repeatedly hit upon progressive themes.

He attacked President Donald Trump’s immigration policies, highlighting the White House’s six-week experiment with systematically splitting parents from their children at the border.

“Yeah, we have to have border security,” Castro said. “But there’s a smart and a humane way to do it. And there is no way in hell that taking babies is a smart or humane way to do it.”

Castro also delved into the issue of race, casting prominent police killings of people of color as symptomatic of America’s wider problems with racial discrimination.

“For far too many people of color, any interaction with the police can become fatal,” Castro said. “If police in Charleston can arrest Dylann Roof after he murdered nine people worshipping at Bible study without hurting him, don’t tell me that Michael Brown, Tamir Rice, Aiyana Jones, Eric Garner, Jason Pero, Stephon Clark and Sandra Bland shouldn’t still be alive today.”

“We’re going to keep saying Black Lives Matter,” the candidate added.

Castro rose to national prominence in 2012 when the then-mayor was selected to give the keynote address at the Democratic National Convention. He joined the Obama administration as the head of HUD two years later, giving him a national profile and feeding speculation that he might become the running mate of his party’s 2016 presidential nominee. (Hillary Clinton ultimately chose Sen. Tim Kaine of Virginia instead.)

Over the last two years, however, Castro’s star has waned, as he stayed out of electoral politics while former U.S. Rep. Beto O’Rourke ran an underdog campaign that brought Texas Democrats within striking distance of winning statewide office for the first time in two decades.

Instead, Castro played a quieter role behind the scenes, supporting dozens of young and progressive candidates around the country through his political action committee Opportunity First.

“He crisscrossed the country in support of candidates,” Latino Victory Fund Director Cristóbal Alex told HuffPost. “He was one of the most sought-after Latino surrogates in the country.”

Castro had already indicated his intentions to run, making a trip to Iowa in August ahead of the midterm elections, releasing a memoir in October and launching an exploratory committee in December, which gave him the legal ability to begin raising campaign money.

In a video announcing the exploratory committee last month, he highlighted the importance of good health care, education and a clean environment. He also stressed the value of hard work, which he said he and his twin brother, Rep. Joaquín Castro (D-Texas), learned from their immigrant grandmother and their single mother.

“She taught my brother and me that if you want to make a change in your life, in your community, you don’t wait, you work,” Julián Castro said of his mother in the video. “So I’m taking a lesson from my mother — if we want to see a change in this country, we don’t wait. We work. We make our future happen.”

In the Democratic primary, Castro will likely face off against Massachusetts Sen. Elizabeth Warren, who recently announced that she had launched her own exploratory committee. The primary is expected to be packed with contenders, including several other senators and former Vice President Joe Biden.

U.S. Rep. Tulsi Gabbard (D-Hawaii), an Iraq War veteran who backed Bernie Sanders in the 2016 Democratic presidential primary, announced Friday that she too would run.

This story has been updated throughout.