Nearly eight months after Election Day, Al Franken, a former comedian and an author, appeared certain on Tuesday to become the next United States senator from Minnesota, giving the Democratic Party at least symbolic control over Senate filibusters.

Outside his St. Paul home, the incumbent, Norm Coleman, a Republican who had held the seat for one term, conceded the election to Mr. Franken, bringing an end to a lengthy battle that had resulted in thousands of pages of legal documents, cost tens of thousands of dollars, and had left many ordinary Minnesotans weary.

Mr. Coleman’s announcement followed a unanimous state Supreme Court ruling on Tuesday in Mr. Franken’s favor. There, the case had centered, in part, around whether some absentee ballots had been wrongly excluded and standards had been inconsistent, as Mr. Coleman contended.