People should be "very suspicious" of anything President Donald Trump's former attorney Michael Cohen says, as he's in the "hot seat," Sen. Lindsey Graham said Sunday.

"The one thing about Michael Cohen is I've never seen a lawyer behave this way in my entire life, and I’ve been a lawyer most of my adult life" the South Carolina Republican told Fox News' Maria Bartiromo on "Sunday Morning Futures."

"When it comes to Michael Cohen, you should be very suspicious of anything he says," Graham added. "He's on the hot seat and he's looking at going to jail, so people like him are subject to making things up."

Graham pointed out that Trump's current attorney, Rudy Giuliani, has complained that a leaked tape of Cohen and Trump talking about a payoff to a former Playboy model was "played with."

Cohen has already testified to Congress about his conversations with Trump, said Graham. Further, he noted, the president's former lawyer last week claimed he told Trump about a meeting at Trump Tower between Trump's oldest son, Donald Jr., and Russians, after Trump Jr. had been promised dirt on Democratic nominee Hillary Clinton.

“This idea that he told Trump about the Russia meeting before it happened is, to us, very much new news,” said Graham, calling on Cohen to return to Congress and tell what he says he knows under oath.

Graham said he doesn't know if Cohen would return to Congress for further testimony, but he finds it odd that the attorney would communicate to special counsel Robert Mueller by leaking stories to NBC News.

"To every American, if I were you, I would be very suspicious of Michael Cohen right now," said Graham, adding that he is tired of Trump being "tried in the media."