Franken, who left his Air America radio show Wednesday, formally announced he will seek the Senate seat held by Republican incumbent Norm Coleman. Franken made the announcement on the radio program and also on his Web site.
In a video statement on his Web site, Franken, a former "Saturday Night Live" writer and performer, acknowledged Minnesotans had a right to be skeptical as he seeks the Democratic nomination.
"I want you to know: nothing means more to me than making government work better for the working families of this state," he said. "And over the next 20 months I look forward to proving to you that I take these issues seriously."
Franken is a native Minnesotan who was raised in St. Louis Park and Albert Lea.
"Given his blind partisanship and extreme anger, Al Franken is the last person Minnesotans need in the United States Senate," said a statement issued by Minnesota Republican Party Chairman Ron Carey.