“Here’s what I would tell Adam Schiff,” Graham said. “Do you really want to start calling other members, Republican members of Congress in oversight? Do you want me to call you to the Senate as part of Senate oversight?”

The big picture: Graham also declared that he will seek a quick end to the impeachment trial, regardless of whether President Trump wants to call more people to testify.

“When 51 of us say we’ve heard enough, the trial is going to end,” Graham said. “The president’s going to be acquitted. He may want to call Schiff, he may want to call Hunter Biden, he may want to call Joe Biden. But here’s my advice to the president: If the Senate is ready to vote and ready to acquit you, you should celebrate that.”