Julián Castro, former Obama Cabinet member, announces 2020 presidential run

Julián Castro, the former mayor of San Antonio and secretary of Housing and Urban Development, formally announced his 2020 presidential campaign Saturday, joining what will be a very crowded field.

What are the details?

Castro, one of the most high-profile Democrats to ever seek the party's presidential nomination, announced his campaign in San Antonio, according to the New York Times.

"When my grandmother got here almost a hundred years ago, I'm sure that 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," Castro said.

Castro's entry into the race was widely expected after he formed an exploratory committee last month. He has also visited Iowa and Nevada — two of the earliest primary and caucus states — in addition to publishing a memoir last year, a common first move for future presidential candidates.

As Fox News noted, Castro is running on a progressive platform that includes universal health care and affordable housing.

Castro, 44, will face a crowded field packed with powerhouse names. Former Rep. John Delaney (D-Md.) and Rep. Tulsi Gabbard (D-Hawaii) have already announced definitive intentions to run for president in 2020. Sen. Elizabeth Warren (D-Mass.) announced her exploratory committee last week. Vice President Joe Biden, Sens. Cory Booker (N.J.), Kamala Harris (Calif.), Kirsten Gillibrand (N.Y.), and Bernie Sanders (I-Vt.) are also widely expected to join the race in the coming months.

Castro's identical twin brother, Rep. Joaquín Castro (D-Texas), will serve as campaign chairman, Castro's campaign said.

How did the GOP respond?

Republican National Committee spokesman Michael Ahrens dismissed Castro's campaign as "obviously just another desperate attempt to become someone else's running mate."

"Julián Castro has made history by becoming one of the biggest lightweights to ever run for president. He was a weak mayor who couldn't even handle being HUD secretary," Ahrens said.