Former U.S. Rep. Chaka Fattah's chances of staving off his decade-long prison sentence dimmed Thursday as a federal appellate court denied his bid to stay free while he appeals his conviction on corruption-related charges.

The U.S. Court of Appeals for the Third Circuit denied Fattah's request, along with similar pleas from two of his codefendants, with a terse, one-page order that offered no explanation for its decision.

"We are disappointed in the court's ruling," said Mark Lee, one of the former congressman's lawyers. It was not immediately clear whether he would attempt to appeal the decision.

Fattah, a West Philadelphia Democrat who served nearly two decades in Congress, is set to begin serving his sentence Jan. 25.

But since receiving the second-longest prison term ever imposed on a member of Congress last month, Fattah and his supporters have turned to any means available to secure a reprieve - including lobbying the White House for a presidential pardon.

Minutes after Thursday's ruling,, a website that claims it is run by former Fattah staffers, released a Jan. 1 letter signed by Therman Evans, a New Jersey pastor, and Lanny Davis, a Washington consultant, hired spokesman, and former counsel to former President Bill Clinton.

The men urged President Obama to absolve Fattah, citing what they described as "undisputed" misconduct by Justice Department investigators and U.S. District Judge Harvey Bartle III, who presided over Fattah's trial last year.

Many of the issues raised in the letter have been vigorously challenged by prosecutors and rejected in Bartle's earlier rulings. They echoed some of the claims Fattah's legal team raised in the bid that the Third Circuit denied Thursday.

"We have known him for 30 years, and know firsthand his unmatched contributions to improving the life chances of tens of millions of Americans," Evans and Davis wrote. "Considering his record of service and the recognized irregularities in the process for this case, I ask that you consider assisting Mr. Fattah, his family and those charged with him in finding relief through presidential action."

Fattah, 60, had argued that his sentence should be delayed because of his likelihood of success in appealing his conviction on charges including racketeering, bribery, money laundering, and fraud.

In their legal briefs, his lawyers argued that Bartle had improperly removed a holdout juror from the panel after deliberations had already begun.

The former juror, a Lancaster County man, has said he was not convinced by the evidence, and would have acquitted Fattah and his codefendants. But other members of the panel told the judge that the man was ignoring the evidence, refusing to deliberate, and appeared to have a bias against the government.

A court clerk also testified that the man had vowed in front of her to hang the jury "no matter what."

Fattah also argued that his bribery convictions could be overturned under a U.S. Supreme Court decision issued days after the jury's verdict in his case.

The ruling - in the case of former Virginia Gov. Robert McDonnell - narrowed the legal definition of bribery. Though Bartle, in his own ruling last month, concluded that Fattah's conduct on behalf of a wealthy fund-raiser who bribed him in pursuit of a White House appointment met even the new standard set by the high court's decision.

What's more, the judge wrote, Fattah's conviction for unrelated crimes involving his misuse of taxpayer money, federal grant funds, and charitable donations to pay off his personal and political debts all ensured that the former congressman would still face a substantial prison term should his bribery conviction be overturned.

Both issues are likely to resurface when Fattah and his codefendants file their full appeals brief before the court later this year.

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