MINNEAPOLIS (Reuters) - Former funnyman Al Franken hopes to convince Minnesotans that he can represent them in the buttoned-down halls of the U.S. Senate. So for now, jokes are off the record.

Democratic senatorial candidate Al Franken speaks to delegates after receiving the Minnesota Democratic-Farm-Labor (DFL) Party endorsement during the 2008 Minnesota State DFL convention in the Mayo Civic Center in Rochester, Minnesota, June 7, 2008. REUTERS/Eric Miller

At a gathering of Democratic activists last week, the author, one-time liberal radio show host and former star of the late-night sketch comedy program “Saturday Night Live” swapped quips with supporters -- after ensuring a reporter would not write them down.

Wearing a sober pinstripe suit, Franken vowed to defend the government programs that helped his wife through a hardscrabble childhood and called for universal health care and an end to the Iraq war. He promised a tough campaign against incumbent Republican Sen. Norm Coleman.

“Norm Coleman is going to try to run away from his record,” Franken said. “I’m not going to let him.”

But observers say it is Franken’s record that could complicate his prospects in the November election.

Even in a state that once elected former professional wrestler Jesse Ventura as governor, the author of “Lies and the Lying Liars Who Tell Them: A Fair and Balanced Look at the Right” must convince voters that he is serious, analysts say.

“If you’re the challenger, you only win by putting the incumbent in the spotlight. Well, for the past two months, Al Franken’s been in the spotlight,” Carleton College political science professor Steven Schier said.

Franken secured the Democratic endorsement over the weekend after courting each of the 1,400 delegates that attended the convention. He had raised $9.4 million for his bid by the end of March, more than the $8.7 million raised by Coleman.

A Franken win in this battleground state would help Democrats solidify their precarious control of the Senate. Most polls show Coleman leading, but The Cook Political Report, a Washington newsletter, rates the race a toss-up.

Republicans have mined provocative statements from “Saturday Night Live” and Franken’s books and radio show to paint him as undignified and too edgy for a state that prides itself on civility.

“There’s a lot to work with there,” Minnesota Republican Party spokesman Mark Drake said. “Things you can’t say in a newspaper, he said them, and he said them about people he’d have to work with in Washington.”

‘WRITING PORN’

Several Democratic members of the Minnesota congressional delegation have said they are worried that a sexually explicit column Franken penned for Playboy magazine in 2000 could distract from issues like the economy, health care and Iraq.

Coleman has also taken a dig.

“Eight years ago, I was making the streets of St. Paul safer and he was writing porn,” the former mayor and prosecutor said at the Republican state convention on May 30.

Another setback has been the revelation that Franken paid income taxes in the wrong states between 2003 and 2006. Franken blamed an accounting error and paid $70,000 to 17 states.

Franken has apologized for the Playboy column, but he said he won’t explain away his past.

“If I tried to put things in context or explain things as satire, and explain that satire involves hyperbole and irony and absurdity and parody of style ... that’s all I’d do,” he said in an interview.

He said his books and radio show have given him a solid grounding in policy, and noted that two of his movies that tackled alcoholism are used widely in sobriety clinics.

The real scandal, he said, is Coleman’s tenure in the Senate. As head of the Permanent Subcommittee on Investigations, Coleman opted to focus on the United Nations, a favorite target of conservatives, rather than the botched Iraq war, Franken said.

“He was put on that committee to not do his job,” he said.

Coleman, who ran for the Senate at the request of President George W. Bush in 2002, has emphasized his independence as Bush’s popularity has plunged in recent years.

A Coleman spokesman said he has worked closely with Democrats on the subcommittee to examine Iraq reconstruction and border security, and has voted against his party when he thought it would help Minnesota.

“Minnesotans do know the difference between a senator who is qualified to do the job, and a satirist who won’t even explain what he meant when he attacked people throughout the years,” Coleman spokesman Luke Friedrich said.

But Franken also will be able to draw on the fervent support of those who see him as a hero.

“Al was the only one who was standing up for us when Rush Limbaugh was beating us up pretty badly,” said Roann Carter, a Democratic activist from Minneapolis.