A U.S. federal judge has denied a motion by George Papadopoulos, a former aide for Donald Trump's 2016 presidential campaign, seeking to postpone his sentence pending a separate case he hoped would lead to his conviction being overturned.

Papadopoulos sought the delay to his 14-day jail sentence until an appeals court rules in a separate case challenging the constitutionality of special counsel Robert Mueller's appointment.

But in an order Sunday, U.S. District Court Judge Randy Moss said Papadopoulos' arguments failed to justify a delay.

"The court, accordingly, concludes that Papadopoulos' motion for a stay pending his appeal of this decision lacks merit," Moss wrote in his ruling. "Plaintiff's motion to continue bail and motion to stay his surrender date are hereby denied."

Papadopoulos had filed an initial motion on Nov. 16, nearly two months after the deadline for appealing his conviction or sentence. He followed up with a request to delay his sentence pending that motion on Wednesday, the day before Thanksgiving.

"Papadopoulos waited until the eleventh hour to seek relief; indeed, he did not file his second motion — the stay request — until the last business day before he was scheduled to surrender to serve his sentence," Moss' 13-page order states. "He has only his own delay to blame.

Papadopoulos pleaded guilty last year to lying to federal agents about his interactions with Russian intermediaries during the 2016 presidential campaign. He also forfeited most of his rights to contest his conviction.

His lawyer argued that the appellate case could constitute new evidence that could allow him to mount a challenge. That case was brought by a witness refusing to comply with a Mueller grand jury subpoena.

Papadopoulos' sentence, issued by Moss on Sept. 7, was far less than the maximum six-month sentence sought by the government but more than the probation that Papadopoulos and his lawyers had asked for. Moss at the time noted that many similar cases resulted in probation but said he imposed a sentence of incarceration partly to send a message to the public that people can't lie to the FBI.

Papadopoulos, the first campaign aide sentenced in Mueller's investigation, triggered the initial Russia investigation two years ago. Memos written by House Republicans and Democrats and now declassified show that information about Papadopoulos' contacts with Russian intermediaries set in motion the FBI's counterintelligence investigation in July 2016 into potential coordination between Russia and the Trump campaign. That probe was later taken over by Mueller.

The White House has said that Papadopoulos was a low-level volunteer on the campaign.