Washington (CNN) South Carolina Republican Sen. Lindsey Graham says he advised President Donald Trump not to halt special counsel Robert Mueller's investigation -- or the President would risk undermining the Republican Party during November's midterm elections.

At an event on Monday hosted by the Greenville County GOP in South Carolina, Graham and fellow South Carolinian Rep. Jeff Duncan were asked by an audience member why they won't "step up and stop the Mueller investigation."

"Did Trump ask that question? He must have mentioned that about 20 times," Graham said referring to his round of golf with the President in New Jersey over the weekend.

Graham then explained to the audience that if Trump were to end the Mueller probe, he believes it would lead to significant losses to the GOP during the midterm elections in November.

"I want to win in November. If we stop the Mueller probe tomorrow, you wouldn't be able to talk about anything else," he continued. "I told the President this. I promise you, you'll be treated fairly. I promise you that the people who put the Clinton investigation in the tank -- they're going to have their day too."

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