Democrat Julian Castro is the former secretary of the Department of Housing and Urban Development under former President Barack Obama and a former mayor of San Antonio, Texas.

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Castro, 44, was named HUD secretary in 2014 by then-president Barack Obama and eyed as a potential vice-presidential candidate on the Democratic ticket with Hillary Clinton in 2016.

Here are six things to know about Castro:

1 - Castro made his mark as a politician when he became the youngest city councilman in San Antonio history in 2001 at the age of 26. He served until 2005 when he decided to run for mayor.

2 - Castro lost his first bid for mayor of San Antonio, but ran again in 2009 and won with 56 percent of the vote. He was re-elected in 2011 by an 82 percent margin.

3 - Castro rose to national prominence in 2012 when he became the first Hispanic to deliver a keynote address at the Democratic National Convention.

4 - Castro has a twin brother who is also a politician. Joaquín Castro has represented Texas’ 20th congressional district since 2013.

5 - Castro, who was born in San Antonio on Sept. 16, 1974, is graduate of Stanford University and Harvard Law School. He married Erica Lira Castro in 2007.

6 – Castro formed an exploratory committee for a possible 2020 run for U.S. president.