WASHINGTON — Julian Castro, the former Housing and Urban Development Secretary and mayor of San Antonio, launched his presidential campaign on Saturday, joining what is expected to be a crowded field of contenders for the Democratic nomination.

Castro is the first Latino to enter the race, and at 44 will likely be among the youngest. His brother, Rep. Joaquin Castro (D-Texas), introduced him.

“When my grandmother got here almost a hundred years ago, I’m sure she never could have imagined that just two generations later, one of her grandsons would be serving as a member of the United States Congress and the other would be standing with you here today to say these words: I am a candidate for President of the United States of America,” he said at the rally.

The Castros grew up in an impoverished neighborhood of San Antonio and were raised by a single mother.

In his announcement speech, Castro called for Medicare for all, alleviation of college debt, reform of the criminal justice system, housing affordability and reforms to the immigration system.

He cited President Trump’s visit this week to the border city of McAllen, Tex., and his claim that there was an “invasion” at the border and a “national security crisis.”

“Well, there is a crisis today, and it is a crisis of leadership. Donald Trump has failed to uphold the values of our great nation,” Castro said. “Yes, there are serious issues that need to be addressed in our broken immigration system, but seeking asylum is a legal right, and the cruel policies of this administration are doing real harm and damage.”

Castro talked of how his grandmother, at seven years old, emigrated to the U.S. and was separated from her dying mother.

“Even as a 70-year-old woman when she remembered those moments she would cry, like the seven-year-old girl she was when it happened, because she never had the chance to say goodbye to her mom. Yeah, we have to have border security, but there is a smart and humane way to do it. And there is no way in hell that caging babies is a smart and humane way to do it.”

He also said that he would recommit the United States to the Paris climate agreement. The Trump administration is withdrawing from the accord.

Castro also vowed to decline contributions from political action committees, taking a position that is likely to be a litmus test for a number of progressive supporters dismayed by the role of money in politics.

Castro formed an exploratory committee in December. John Delaney, a former congressman from Maryland, launched his presidential bid in 2017, and Sen. Elizabeth Warren (D-Mass.) announced the formation of an exploratory committee on Dec. 31. Rep. Tulsi Gabbard (D-Hawaii) will announce on CNN’s “The Van Jones Show” on Saturday that she is also running.

Sen. Kamala Harris (D-Calif.), who has been in the midst of a book tour, also is expected to launch a presidential bid soon. She appeared on “The Late Show with Stephen Colbert” on Thursday and tested that she “might” run.