US President Donald Trump says he believes the American economy would tank if he were to be impeached.

Mr Trump was asked in an interview with Fox & Friends in the US if he believes Democrats will launch impeachment proceedings if they win the House in November, as many suspect.

He said: "If I ever got impeached, I think the market would crash. I think everybody would be very poor".

Mr Trump said Americans would see economic "numbers that you wouldn't believe in reverse".

"I don't know how you can impeach somebody who's done a great job," Mr Trump said.

But Mr Trump also expressed doubt that that would ever happen.

"I don't know how you can impeach somebody who's done a great job," he said.

Donald Trump said no US president “has ever done what I have done”. Picture: AP
Donald Trump said no US president “has ever done what I have done”. Picture: AP

Mr Trump also said that he would give himself an "A+" if asked to grade his performance in office so far, citing his successful appointment of Justice Neil Gorsuch to the Supreme Court and predicting that Brett Kavanaugh, his next high court pick, will be confirmed as well.

"I give myself an A+. I don't think any President has ever done what I have done," Mr Trump said.

"We haven't even been [in] two years. Biggest tax cuts in history. Soon to be two unbelievable Supreme Court justices, I'm sure that Justice Kavanaugh will be approved. Justice Gorsuch has been a star.

"You look at all the things we have done with regulations, the economy is the best it has ever been in history. The only thing I'm doing badly in is the press doesn't cover me fairly," Mr Trump said.

The US President also took the opportunity to once again take aim his Attorney-General Jeff Sessions because "he never took control of the Justice Department", a barb seemingly aimed at Mr Sessions for recusing himself from the federal investigation into Russian interference in the 2016 US election.

"I put in an Attorney-General that never took control of the Justice Department, Jeff Sessions," Mr Trump told Fox and Friends on Thursday. "It's an incredible thing."

Mr Trump has continued to criticise Mr Sessions since he announced last year that he would recuse himself from any federal probe of Russian meddling in the election. His recusal led to the appointment by the Justice Department of special counsel Robert Mueller a month later.

Mr Trump told Fox and Friends that "Sessions shouldn't have recused himself" or at least, "should have told me".

"He took the job and then recused himself," Mr Trump said. "What kind of man is this? By the way, the only reason I gave him the job, I felt loyalty. He was an original supporter."

But when asked whether he would sack Mr Sessions because of the Attorney-General's recusal has authority over the Mueller probe, Mr Trump said he wants "to stay uninvolved".