Sen. Lindsey Graham said Monday night that he has told President Donald Trump that ending the special counsel investigation of Robert S. Mueller III would undermine GOP chances in November.

The South Carolina Republican, who played golf with Trump on Sunday in New Jersey and discussed several issues with the president, was asked about the investigation of Russian efforts to interfere with the 2016 presidential election at a Monday evening event hosted by the Greenville County Republican Party.

“Did Trump ask that question? He must have mentioned that about 20 times,” Graham quipped in response to an audience question about ending the Mueller probe.

Graham said that his message to Trump was in part about the reality of what Republicans could face in November if the Mueller probe is compromised by the actions of the Trump administration or congressional Republicans.

Watch: Graham on Mueller Conversation With Trump: ‘You Just Gotta Ride It Out’