President Trump on Sunday indicated that nothing will dissuade him from his belief that he won November's election, even as his lawsuits fall flat and he fails to produce evidence of widespread fraud in the contest President-elect Joe Biden won.

"It's not like you're going to change my mind. In other words, my mind will not change in six months. There was tremendous cheating here," Trump told Maria Bartiromo on "Sunday Morning Futures" in his first television interview since Election Day.

Trump spent most of the 45-minute phone call with Bartiromo levying unproven and baseless allegations that letter carriers, Dominion Voting Systems, Republican officials and mail-in ballots were all to blame for his defeat to Biden nearly a month ago.

The president also questioned the court system, which has thus far rejected his legal team's attempts to overturn the election, citing a lack of evidence, and he blasted the FBI for failing to more aggressively look into his unfounded claims.

Trump showed no indication he was prepared to concede, signaling he was hopeful his case would go to the Supreme Court days after a judge in Pennsylvania dismissed one challenge for lack of standing. 

"I’m going to use 125 percent of my energy to do it," Trump said when asked how he planned to prove his claims. "You need a judge that's willing to hear a case. You need a Supreme Court that's willing to make a real big decision."

Trump also expressed disbelief that the courts had rejected the claims of a sitting president.

"What kind of a court system is this?" Trump asked at one point, explaining that he would like to file "one nice, big, beautiful lawsuit talking about this and many other things with tremendous proof."

The Trump legal team has filed lawsuits in Michigan, Georgia, Pennsylvania, Arizona and Wisconsin. Many of those challenges have been tossed out for lack of standing or do not apply to enough votes to change the outcome of the election. The president and his team have repeatedly claimed outside the courtroom that poll watchers were not allowed to observe or that Democratic officials tampered with ballots. But in the courtroom, under penalty of perjury, they have failed to produce evidence of fraud.

Bartiromo did not push back on Trump's claims during Sunday's interview, instead asking why there wasn't more outrage about what the president was asserting. 

"You have laid out some serious charges here. Shouldn't this be something that the FBI is investigating? Are they?" Bartiromo asked. 

"Missing in action. Can’t tell you where they are," Trump said, asking, "What happened to Durham?" in reference to an investigation into the origins of the Russia probe that the president had expressed optimism would lead to charges against Obama administration officials.

"This is the biggest thing you could be looking at," Trump added. "Where are they? I’ve not seen anything. They just keep moving along, and they go on to the next president."