Sen. Lindsey Graham said Americans would appreciate if President Donald Trump said he is sorry for his mistakes.
Graham's comments came during an interview on CBS "This Morning."
"When you have the highest official in the land, the president of the United States, accusing his predecessor of illegal activity with no evidence that hurts our democracy."
Graham said Trump will "suffer over time with the American people" if he refuses to back down on his claims former President Barack Obama wiretapped Trump Tower during the presidential campaign.
"Here's what I'd say to the president," Graham said. "It doesn't mean you're above having to say you're sorry . . . to apologize if you did something wrong. I think most people would appreciate it if the President of the United States had the ability to say: 'I made a mistake. I'm sorry.'
"If you can't do that then that's going to hurt you over time with the American people. Because there'll come a day when you'll have to look the TV camera in the eye and tell them North Korea is about to develop a missile to hit our homeland and 'I want to stop them.'
"You need that credibility. So, I think President Trump is going to put his credibility at risk if he continues this narrative without proof."
FBI Director James Comey had testified on Capitol Hill that he "has no information that supports" Trump's allegation that Obama wiretapped Trump Tower, NBC News reported.