Sen. Mike Lee doesn't like it when GOP presidential candidate Donald Trump claims that Texas Sen. Ted Cruz has no friends in the Senate.

"It makes me mad when Trump says that," Lee told the Washington Examiner this week. "Ted Cruz is my friend, so if Mr. Trump or anyone else is saying Ted Cruz doesn't have any friends in the Senate, I can say unequivocally, that is not true. I am his friend and I don't regard myself as alone in that either."

Lee in 2010 became the first Tea Party candidate to upset an incumbent GOP senator.

Trump has spent weeks hitting Cruz for failing to garner the endorsement of any fellow senators, but Lee said he has only remained on the sidelines because some of his "close friends" are running for president, such as Kentucky Sen. Rand Paul and Florida Sen. Marco Rubio.

Paul's departure from the race simplifies the problem for Lee, but only a little. "If either Ted or Marco were the only one of my friends in there, I'd endorse either one," he said. "If it came down to a two-person race, say, between Cruz and Trump or Rubio and Trump, then it's an easy decision to make."