New York, New York - Donald Trump said Monday that he has a "real problem" with the judge handling his New York criminal case – and that he should be on the campaign trail instead of in court.

"We're not going to be given a fair trial," Trump told reporters outside the Manhattan courtroom after jury selection ended for the day in his "hush money" trial, one of four separate criminal cases he faces.

Trump also criticized Judge Juan Merchan for rejecting his request that he be allowed to attend a Supreme Court hearing next week.

Trump argues that, as a former president, he should be immune from criminal prosecution, a question the nation's highest court is to weigh in arguments on April 25.

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"The judge, of course, is not going to allow us to go to that," Trump said. "He thinks he's superior, I guess, to the Supreme Court."

Trump has repeatedly criticized the judge presiding over the trial, and Merchan rejected a request by the former president's attorneys on Monday that he recuse himself from the case.

"We've got a real problem with this judge," Trump said. "He's a very conflicted judge."

Trump denounced the case – brought by Manhattan District Attorney Alvin Bragg, a Democrat – as a "political witch hunt" and said he should be out campaigning in his 2024 White House bid.

"I'm not in Georgia, or Florida or North Carolina, campaigning like I should be," the Republican presidential candidate said. "This is about election interference."

Trump, the first ex-president to face criminal charges, is accused of falsifying business records for allegedly paying hush money to a porn star just days ahead of the 2016 presidential election, to cover up a 2006 sexual encounter.