President Trump and his Republican allies are "running out of runway" after the Supreme Court declined to hear a challenge to a Pennsylvania law expanding mail-in voting, George Washington University Law Professor and Fox News contributor Jonathan Turley said Tuesday.

"We have talked in the past about how the president was running out of runway," Turley told "Special Report". "And at this point, to really make a difference, he would have to land a jumbo jet on a postage stamp. I mean, he does not have a lot of runway left. This was considered his strongest case for the Supreme Court and the court system has proven that it is independent in reviewing these claims."

The high court, which includes three justices nominated by Trump, left intact a decision from the Pennsylvania Supreme Court to toss a lawsuit from Rep. Mike Kelly, R-Pa. that contested the 2019 law, landing a "big blow" to the president and his legal team, Turley explained.

The GOP appeal to the high court was referred to Justice Samuel A. Alito Jr., who then referred it to the full court.  

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The newest justice, Amy Coney Barrett participated in the vote, despite Democrats repeatedly spreading "these conspiracy theories that she was put on the court to kill the ACA [ObamaCare] or steal the election" throughout her confirmation process, Turley observed. 

"It would be nice if some Democratic senators actually apologized to people like Barrett and others," Turley added.

JUDGE DISMISSES FLYNN CASE AFTER TRUMP PARDON

Shifting to U.S. District Judge Emmet Sullivan's dismissal of the criminal case against former National Security Adviser Michael Flynn earlier Tuesday, Turley said he found it "really grossly inappropriate for him [Sullivan] to essentially declare a verdict of a person who wasn't even sentenced. 

"That's what this was. And, you know, judges usually don't even address the guilt of a defendant until sentencing," he added. "They certainly avoid that when you are having a dismissal of a case, they don't talk about guilt or innocence."

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Trump pardoned Flynn in late November after Sullivan refused to automatically grant the Justice Department's motion to dismiss Flynn's case earlier this year.

Sullivan's handling of the Flynn case was "gratuitous," Turley said, "and it was wrong for the court to do it."