Brynn Anderson, AP
From left, New York City Mayor Bill de Blasio, Rep. Tim Ryan, D-Ohio, former Housing and Urban Development Secretary Julian Castro, Sen. Cory Booker, D-N.J., Sen. Elizabeth Warren, D-Mass., former Texas Rep. Beto O’Rourke, Sen. Amy Klobuchar, D-Minn., Rep. Tulsi Gabbard, D-Hawaii, Washington Gov. Jay Inslee, and former Maryland Rep. John Delaney pose for a photo on stage before the start of a Democratic primary debate hosted by NBC News at the Adrienne Arsht Center for the Performing Arts, Wednesday, June 26, 2019, in Miami.

SALT LAKE CITY — Former Housing and Urban Development Secretary Julian Castro and former Texas Rep. Beto O'Rourke briefly sparred during the Democratic primary debates that had Twitter riled up.

Castro said O’Rourke supports section 1325 of the Immigration Act, which would criminalize border crossings. Castro said he would push to repeal this idea.

Castro told O’Rourke, “If you did your homework on this issue” in regards to O'Rourke’s talk about his understanding of border crossings.

"I just think it is a mistake," Castro said.

Twitter reacted to the exchange.