WASHINGTON — Bernie Sanders is warning the Democratic Party not to attack its own candidates in primary battles, as happened in a Houston-area congressional race.

The Vermont senator says it’s “appalling” that the party’s campaign arm, the Democratic Congressional Campaign Committee, targeted Laura Moser, an activist who is running for Congress. She’s endorsed by Sanders’ Our Revolution PAC.

Sanders tells The Associated Press such attacks are “not acceptable.”

Moser is now in a runoff with Democratic front-runner Lizzie Pannill Fletcher after Tuesday’s primary elections. The winner will face Republican incumbent Rep. John Culberson, who’s seeking a 10th term, this fall.

Sanders says he hopes “very much that type of behavior does not occur again.”

He says such attacks are part of the reason “so many people are disgusted with politics.”