A federal appeals court on Friday refused to overturn the conviction of the only lobbyist to go to trial on charges of bribing public officials related to the Jack Abramoff scandal.

Kevin Ring's conviction was upheld by the U.S. Circuit Court of Appeals for the District of Columbia, which called his arguments on appeal "weighty," but not enough to overturn his conviction and sentence of 20 months in prison.

Ring got one of the stiffest terms among the 21 defendants in the investigation. Ring was the only lobbyist defendant to go to trial rather than reach an agreement with the government to plead guilty and cooperate. All the other lobbyists and most of the public officials charged cooperated with prosecutors and received plea deals, most of which did not include prison terms. Abramoff, the ringleader, pleaded guilty and was sentenced to four years in prison.

Ring, who worked under Abramoff, was convicted of giving meals and event tickets to public officials with an intent to corrupt them. Trial Judge Ellen Huvelle allowed evidence of legal campaign contributions, which prosecutors said showed how Ring gained access to public officials. But Huvelle also told jurors they could not consider the contributions as part of the "illegal stream of benefits" Ring was charged with providing officials.

Ring complained that Huvelle overstepped by allowing the legal contributions as evidence. But the appeals court refused to overrule her.