In March, Mr. Brodkorb reported that Mr. Franken’s corporation, Alan Franken Inc., owed $25,000 to the state compensation board in New York for failing to carry workers’ compensation insurance from 2002 to 2005. State officials said they sent Mr. Franken numerous letters on the matter, but received no answer.

Image U.S. Senate candidate and comedian Al Franken talked with a voter at Nina's Coffee Cafe in St. Paul, Minn. in 2007. Credit... Ben Garvin for The New York Times

Andy Barr, a spokesman for the campaign, said Mr. Franken had not known of the oversight by the corporation (which consisted of Mr. Franken, his wife, Franni, and an assistant or two), and received none of the letters. The state’s letters were sent to the Frankens’ New York apartment, officials there say; the couple moved to Minnesota at the end of 2005, though the family still owns the apartment.

In April, Mr. Brodkorb wrote that Mr. Franken’s company was in forfeiture in California. Other reporters found the reason: California authorities said Mr. Franken’s company had failed to pay franchise tax fees from 2003 to 2006, and owed nearly $5,ooo, which Mr. Franken has since paid. Mr. Franken’s company paid no franchise taxes to the state in those years, Mr. Barr said, because Mr. Franken believed his accounting firm had shut down the corporation in 2002.

The reports led Mr. Franken to hire a new team of financial advisers to review his finances. Late last month, Mr. Franken announced the findings: although he had paid state income tax on his earnings, his accountant had, in some cases, paid it to the wrong states. Like baseball players, entertainers are required to pay taxes to states where they earn money. He had paid more than $917,000 in state taxes to New York and Minnesota from 2003 to 2006, but should have sent parts of about that sum (the total should have been about $4,000 higher) to 17 other states where he performed. Mr. Franken’s supporters, and several Democratic-leaning blogs, have dismissed the problems as meaningless, an accountant’s bureaucratic errors.

“We’re in two wars and a recession,” Mr. Barr said. “This is not the time to try to have an election about something else.”

Still the campaign has clearly worried: it created an emergency phone bank one evening to call the more than 1,300 Democratic convention delegates and alternates and deliver the news before it came out the next day in the newspapers.

Many state Democrats (here, the party is known as the DFL for the Democratic-Farmer-Labor Party) dismiss Mr. Brodkorb as a mouthpiece for accusations the Republicans dig up and want to present somewhere more likely to catch on than a press release. Indeed, Mr. Brodkorb, 34, once worked on the campaigns of Republican leaders including Mr. Coleman and last year managed (without pay) the campaign of Ron Carey to become the state’s Republican chairman.