Al Franken plans to run for the U.S. Senate in Minnesota next year with a platform aimed at middle-class families. ((Ann Heisenfelt/AP))

U.S.comedian Al Franken said Wednesday he plans to run for the U.S. Senate in Minnesota next year in a serious attempt to improve the lot of middle-class families.

Calling himself a "comedian by trade,"and not a "typical politician," Franken made the announcement on the last day of his talk show on Air America Radio.

If he receives the Democratic nomination in Minnesota, he will be challenging incumbent Norm Coleman.

"Minnesotans have a right to be skeptical about whether I'm ready for this challenge, and to wonder how seriously I would take the responsibility that I'm asking you to give me," Franken says in a video on his campaign website.

"I want you to know: nothing means more to me than making government work better for the working families of this state, and over the next20 months I look forward to proving to you that I take these issues seriously."

Franken, 55, a former performer on television's Saturday Night Live, will likely be able to attractconsiderable financial backing because of his celebrity status.

ButFranken is expected to be challenged by other Democrats for the seat, including U.S. attorney Mike Ciresi.

'Families are being squeezed'

In the campaign video, Franken talks at length about the problems facing middle-class families.He grew up in the Minneapolis suburb of St. Louis Park.

"These families are being squeezed harder and harder every year," he says.

"Maybe you know what it's like to be one health crisis away from bankruptcy. Maybe you, or your parents or grandparents, can't afford prescriptions. Maybe you have kids, and you're worried about paying for their college. Maybe someone you love is in Iraq, and you don't know how long they'll have to stay there, or what will happen when they come home," he says.

"Middle-class families today struggle with that feeling of insecurity — the sense that things can fall apart without notice, outside of your control."

Franken adds: "Conservatives like to say that people need to pull themselves up by their bootstraps — and that's a great idea. But first, you've got to have the boots."

Americans, he says,need "freedom from fear."

Frankensays he would like to be a Minnesota politicianin the tradition of other Democratic leaders from the state,including Hubert Humphrey and Walter Mondale.

Both Mondale and the late Humphrey, both former U.S. vice-presidents, were U.S. senators from Minnesota.

"Minnesota's public servants might not always look and sound like typical politicians, but they stand by their principles and lead by their values," he says.

Franken, born in New York City, gained prominence as a writer and performer onSaturday Night Live before turning to writing books combining humour and politics.

Hehas three New York Times No. 1 bestsellers to his credit, including 1996's Rush Limbaugh is a Big Fat Idiot and Other Observations, and 2003's Lies and the Lying Liars Who Tell Them: A Fair and Balanced Look at the Right, which dissects U.S. President George W. Bush, television host Bill O'Reilly and other U.S. conservative figures.

He hosted theThe Al Franken Show on radio.

Currently, Franken runs the Midwest Values Political Action Committee, an organization he founded in 2005 to support "progressive" causes in Minnesota.

With files from the Associated Press