Eight months after his election triumph, President Obama scored another critical victory yesterday when the former comedian Al Franken was declared the winner of Minnesota’s unresolved Senate race.

The Minnesota Supreme Court gave a unanimous ruling in favour of Mr Franken over the Republican incumbent Norm Coleman — effectively handing the Democrats control of 60 of the Senate’s 100 seats. That is enough to overcome Republican procedural roadblocks such as filibusters against Mr Obama’s legislative agenda. Mr Franken becomes the Senate’s 58th Democrat but the party can routinely rely on the support of two independents.

The court’s decision came just two days after Minnesota’s Republican Governor Tim Pawlenty conceded that the result was now so long overdue that he was prepared to sign off on whatever judges concluded, choking off any prospect of a challenge to the United States Supreme Court. The ruling will bring to an end a bitter 238-day wrangle in which the lead in the contest switched several times.

Mr Coleman, seeking a second term, won a razor-thin advantage over Mr Franken on November 4, 2008, but the result was close enough to trigger an automatic recount of the 2.4 million ballots. The recount put Mr Franken, a liberal satirist and former writer and actor for the popular Saturday Night Live television show, ahead by a mere 225 votes. That result was then challenged by Mr Coleman, and a judicial panel agreed to add a few hundred previously rejected absentee ballots — which resulted in an expanded lead for Mr Franken of 312 votes.

Yesterday, Minnesota’s top court ordered that Mr Franken be declared the winner. In a unanimous ruling, the court decided that “Al Franken received the highest number of votes legally cast and is entitled under Minnesota statute . . . to receive the certificate of election as United States Senator from the State of Minnesota”. The certificate is required to assume office.

Mr Coleman’s appeal had hinged largely on whether thousands of absentee votes had been unfairly rejected by local election officials. The court rejected that, saying “there is no basis on which voters could have reasonably believed that anything less than strict compliance would suffice”.

Mr Coleman had not ruled out seeking federal court intervention, but last night conceded defeat.

The court’s decision allows Mr Franken to take up his seat when the Senate reconvenes next week after the July 4 holiday.

The longest contested US Senate election on record was the ten-month contest in New Hampshire in 1974, between the eventual winner, John Durkin, and Louis Wyman.

One problem that Democrats could face in actually reaching the 60-vote mark is that two of their oldest members, Edward Kennedy, 77, and Robert Byrd, 91, have often been absent from Capitol Hill this year because of illness. Senators need to be in the chamber to vote.

President Obama has conceded that he does not expect his fellow Democrats in the Senate to become a “rubber stamp” and that he will still have to work to muster the votes to pass his ambitious agenda, which includes overhauling the US healthcare system and curbing global warming.

Nor is the “supermajority” an automatic blessing. The last time either party had a filibuster-proof 60 was in 1979, when the Democrats held 61 and Jimmy Carter — a Democrat — was President. Mr Carter, though, clashed with divided Senate Democrats; so much so that Senator Kennedy challenged him for the party’s 1980 presidential nomination.

Mr Carter won the nomination, but lost the general election to Ronald Reagan, who helped his fellow Republicans to take back control of the Senate.

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