A Minnesota court confirmed Monday that Democrat Al Franken won the most votes in his 2008 Senate race against Republican Norm Coleman, who had already announced plans to appeal the decision.

Coleman has 10 days to appeal to the state Supreme Court. Once the petition is filed, it could further delay the seating of Minnesota’s second senator for weeks.

After a statewide recount and seven-week trial, Franken stands 312 votes ahead. He gained more votes from the election challenge than Coleman, the candidate who brought the legal action.

The state law under which Coleman sued required three judges to determine who got the most votes and is therefore entitled to an election certificate, which is now on hold pending an appeal.

“The overwhelming weight of the evidence indicates that the November 4, 2008, election was conducted fairly, impartially and accurately,” the judges wrote. “There is no evidence of a systematic problem of disenfranchisement in the state’s election system, including in its absentee-balloting procedures.”

In its order, the judicial panel dismissed two attempts by Coleman to subtract votes from Franken over allegations of mishandled ballots in Minneapolis.

The judges also rejected Coleman’s argument that a state board improperly made up for a packet of ballots lost between the election. His lawyers conceded that the ballots’ disappearance rendered them invalid and that Coleman was entitled to review all ballots as part of the recount.

Coleman’s lawyers claimed dozens of ballots were double-counted when their originals couldn’t be fed into optical scanning machines on Election Day. They said it was possible that originals and duplicates were included in the recount.

The ruling diminishes Coleman’s chances of retaining a seat that he won in dramatic fashion in 2002, when he narrowly defeated former Vice President Walter Mondale. Democratic incumbent Paul Wellstone died in a plane crash with two weeks to go in the campaign.

Franken, a former “Saturday Night Live” comic, entered the Senate race more than two years ago. A third-party candidate’s strong showing left Coleman and Franken virtually deadlocked on Election Night, triggering an automatic recount of 2.9 million ballots. Coleman led by about 700 votes before routine double-checking of figures trimmed his edge to 215 votes heading into the hand recount. By the recount’s end in January, Franken had pulled ahead by 225 votes.

Coleman’s trial began in January and his appeal could push the race into May or beyond.

Coleman’s lawyers have said their appeal will mostly center on violations of the constitutional guarantee of equal protection, arguing that counties had differing standards in treating absentee ballots.

Franken’s attorneys argued that no election is absolutely precise and that all counties operated under the same standard.

In addition to the appeal, Coleman can also initiate a new action on a federal level. Either side can appeal an eventual state Supreme Court decision to the U.S. Supreme Court or throw the disputed election before the U.S. Senate, which can judge the qualifications of its members.