Minnesota Court Rules for Franken

UPDATED 4:18 p.m. ET

NOTE: Coleman has now conceded and congratulated Franken on his victory. Read more here.

Former Senator Norm Coleman has lost his appeal to the Minnesota Supreme Court, paving the way for Democrat Al Franken to join the Senate and give his party a filibuster-proof majority – though Coleman's could still appeal the decision in U.S. federal court.

"We affirm the decision of the trial court that Al Franken received the highest number of votes legally cast" in the election, the decision states. The justices also explicitly ruled that Franken is "entitled" under Minnesota law to receive the certificate of election as senator.

The judges stated that Coleman has "not shown that the trial court's findings of fact are clearly erroneous or that the court committed an error of law or abused its discretion." They ruled unanimously for Franken, 5-0.

"Coleman has exhausted all of his state legal options at this point," said CBS News political director Steve Chaggaris. "His choice now is to either appeal to federal courts or concede."

Coleman was initially declared the winner in the Minnesota Senate race after Nov. 4th voting, but Franken came out ahead after a recount. His slim victory held up amid a series of court battles lasting more than seven months that have prompted the longest Senate vacancy in 34 years.

In his appeal to the state Supreme Court, Coleman had sought to overturn a lower court decision and have a number of absentee ballots that had been rejected and not counted under state law opened and possibly counted. The Supreme Court ruled that the lower court decision should not be overturned.

"Coleman had hoped to show that in this election and recount process, there had been differences in the standards and stringency of application used in accepting some ballots, or rejecting others," said CBS News Director of Elections Anthony Salvanto. "The Supreme Court did not find that he’d made that case, and noted that Minnesota’s absentee voters did need to meet the standards laid out by the law."

Minnesota Gov. Tim Pawlenty, a Republican, has indicated that he would sign an election certificate if state courts instructed him to do so. Senate Majority Leader Harry Reid will most likely seat Franken as soon as the certificate is delivered to the Senate. That could happen next week.

Reid released a statement following the decision encouraging Pawlenty "should put politics aside, follow his state’s laws and finally sign the certificate that will bring this episode to an end." Minnesota Secretary of State Mark Ritchie, who must also sign the certificate, has released a statement saying he will do so.

Wary of another Democrat being seated in the Senate, national Republicans have raised money for Coleman's legal battle and repeatedly encouraged him to fight on. With Congress considering President Obama's ambitious agenda on energy, health care and other issues, Franken's addition to the Senate would give Democrats an important advantage in fighting GOP filibusters.

It is not yet known whether Coleman will now seek an appeal to federal and possibly the U.S. Supreme Court.

Franken will be able to take the seat in the U.S. Senate even if Coleman appeals, however, if and when Pawlenty signs the election certificate.

Both Coleman and Franken plan to hold news conferences this afternoon.

"This doesn't mean that legally this is all over," said Chaggaris. "This could last. The question for Coleman is does he want to keep on fighting at this point."

If the decision holds up, Franken will have defeated Coleman by 312 votes in a contest in which 2.9 million ballots were cast.