Sen. Lindsey Graham wants to make oversight of the Department of Justice and the FBI a top priority if he takes the helm of the Senate Judiciary Committee in the next Congress.

The South Carolina Republican is next in line to become Judiciary chairman now that Sen. Chuck Grassley, R-Iowa, has said he’ll return to running the Senate Finance Committee.

“The oversight function would very much be front and center,” Graham said this week after a reporter asked him how he’ll run the committee and whether he’d investigate special counsel Robert Mueller’s handling of the investigation into alleged Trump campaign collusion with Russia.

Graham has become a close confidant of President Trump’s, but is not always a defender of the president. They talk frequently by phone, including this week, when Graham spoke to him about legislation to reform the criminal justice system.

Graham has also criticized Trump at times and supports legislation to protect the Mueller investigation, even though he doesn't think it's necessary

Trump has called the investigation a witch hunt, but has not made any specific move to end it, although some believe the ousting of Attorney General Jeff Sessions is a threat to Mueller.

“The idea of having a check and balance makes sense to me,” Graham said of legislation offered by Sen. Chris Coons, D-Del., and Jeff Flake, R-Ariz., that would make it difficult for the president to fire Mueller. “I would support it if it came to the floor, but I don’t see an imminent threat to Mueller.”

Graham said Session’s replacement won’t try to stop Mueller.

“He understands the position he is in,” Graham said. “He’s probably not going to be the next attorney general but this is a chance for him to show that he can handle responsibility. This enhances his political future if he handles this well. It would be a nightmare for us to truncate the Mueller investigation and I think he understands that.”