WASHINGTON -- The Minnesota Supreme Court yesterday declared former comedian Al Franken the winner of the state's U.S. Senate race, ending an eight-month election saga and giving Democrats a 60-seat majority that would theoretically allow them to block Republican filibusters.

In a unanimous ruling, the court rejected incumbent Republican Norm Coleman's legal arguments that some absentee ballots had been improperly counted, and that some localities had used inconsistent standards in counting votes.

The ruling led Mr. Coleman to concede his Senate seat to Mr. Franken, who could be sworn in as soon as next week, when the Senate returns from a recess. "The Supreme Court has spoken. We have a United States senator," Mr. Coleman said in a news conference outside of his house in St. Paul. "It's time to move forward."

The Democrats now have their largest majority in the Senate since 1978, but their ability to prevent filibusters as they attempt to push President Barack Obama's agenda is likely to prove illusory. A pair of prominent Democrats, Sens. Edward Kennedy of Massachusetts and Robert Byrd of West Virginia, have missed a raft of votes this year because of illness and, while Mr. Byrd was released from a Washington-area hospital yesterday, it is unclear how often either will be present in the chamber.

Efforts to maintain party unity are also hampered by the presence of a clutch of centrist Democrats, such as Sen. Mary Landrieu, D-La., who have said they oppose the so-called public option in health care reform legislation that would seek to create a government program to compete with private insurers.

A number of Senate Democrats representing states that rely heavily on manufacturing jobs have also expressed concern about the climate-change bill that passed the House last week, another Obama priority.

"The idea that you've got 60 reliable Democrats for votes for sweeping policy change simply doesn't work, it's not the reality of it," said Norman Ornstein, a congressional expert at the American Enterprise Institute. "The larger challenge for [Senate Majority Leader] Harry Reid or Barack Obama is managing expectations of people who are thinking when you get 60 votes, you get do to whatever you want, and they most assuredly do not."

In a statement, the White House said Mr. Obama looks "forward to working with Senator-elect Franken to build a new foundation for growth and prosperity by lowering health care costs and investing in the kind of clean-energy jobs and industries that will help America lead in the 21st century."

Mr. Franken, joined by his wife, Franni, at a news conference in Minneapolis, said, "I can't wait to get started." But he played down the importance of the fact that he will become the 60th Democrat in the chamber. "Sixty is a magic number, but it isn't because we know that we have senators who -- Republicans who are going to vote with the Democrats, with a majority of Democrats on certain votes, and Democrats that are going to vote with majority Republicans on others.

"So it's not quite as a magic number as some people may say. But I hope we do get President Obama's agenda through."

While he will be a back-bencher in his caucus, he will also be thrust almost immediately into one of the summer's highest-profile pieces of political theater, the confirmation hearings for Supreme Court nominee Sonia Sotomayor. Democrats have been holding a Judiciary Committee seat for the Harvard-educated Mr. Franken, who will also serve on the Health, Education, Labor and Pensions Committee, a prime perch in the health care debate.

A longtime Democratic activist, Mr. Franken is likely to be a reliable vote for the party on nearly every issue and has largely praised Mr. Obama's performance throughout the year. But beyond the Sotomayor hearings, he has indicated that he will attempt to keep a low profile in Washington.

Earlier this year, he said he would seek to replicate the model of Secretary of State Hillary Rodham Clinton, when she first became a New York Democratic senator, generally eschewing major speeches in her first few years on Capitol Hill to focus on learning the Senate's internal dynamics and trying to avoid upstaging her colleagues.

"A lot of people have been sort of saying, 'You should really study Hillary's model of being a senator," Mr. Franken said. "She worked across party lines, wasn't grabbing the microphone."

Before his Senate bid, Mr. Franken had gained a reputation as a partisan and acerbic Democrat. After leaving "Saturday Night Live" in 1995, he wrote books including "Rush Limbaugh Is A Big Fat Idiot" and "Lies and the Lying Liars Who Tell Them: A Fair and Balanced Look at the Right," and hosted a show on the liberal Air America network.

But he largely downplayed both his humor, temper and partisan background in his two-year campaign against Mr. Coleman, who led that race by 206 votes out of almost 3 million cast after the Nov. 4 vote, but fell behind Mr. Franken by 225 votes when absentee ballots were counted.