Senate Majority Leader Mitch McConnell (R-Ky.) has urged Republican presidential frontrunner Donald Trump to condemn the violence that has erupted at his rallies.

“I mentioned to him that I thought it would be a good idea for him no matter who starts these violent episodes to condemn it,” McConnell told reporters on Tuesday.

McConnell spoke just hours after Trump called him as part of the GOP frontrunner’s effort to get the Republican establishment to back his campaign and help unify the party.

His comments are a sign that the clashes between Trump supporters and protestors are worrying Senate GOP leaders.