US Democrats consolidate control of the Senate with 61 seats

A 60-vote majority would be enough to override Republican procedural hurdles such as filibuster, and muscle through key parts of President Obama's agenda, including measures to provide health insurance to all Americans and combat global warming while moving the country toward energy independence.

On election night last November, electronic voting machines gave Mr Franken's Republican opponent Norm Coleman a 215-vote lead. After a state-wide manual recount Mr Franken was declared the winner, but Mr Coleman fought the result in court. Mr Coleman has not publicly ruled out continuing his fight in the federal courts.

In earlier court hearings, his legal team complained that a number of absentee ballots had been unfairly rejected by local officials.

But the Minnesota Supreme Court rejected Mr Coleman's arguments.

Mr Franken first came to prominence as a comedian, appearing on Saturday Night Live. He later became a best-selling author and a host on the liberal Air America radio station.

Democratic Senate Majority Leader Harry Reid issued a statement to "congratulate Senator-elect Al Franken, the next senator from the state of Minnesota".

He added: "The people of Minnesota will now finally get the brilliant and hardworking new senator they elected in November and the full representation they deserve".

The Minnesota ruling follows the announcement by Senator Arlen Specter from Pennsylvania who defected from the Republican Party to the Democrats.

“This is a painful decision" Specter told reporters of the stunning move that boosted his 2010 re-election chances to a sixth six-year term by sidestepping a tough challenge in the Republican primary from conservative Pat Toomey.

Senate Majority Leader Harry Reid promptly welcomed the 79-year-old moderate into the ranks of Democrats who already control 60 seats in the 100-member Senate.

The last time either party held 60 Senate seats was in 1978, when the Democrats had 61.