“This looks like random incompetence mostly,” said Lawrence Jacobs, a political scientist at the University of Minnesota. “But Franken has taken a pounding, getting tattooed by story after story, which is preventing him from making this a referendum on the incumbent.”

In March, Mr. Brodkorb reported that Mr. Franken’s corporation, Alan Franken Inc., owed a penalty of $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 12 letters on the matter, but received no answer.

Mr. Franken, who has since paid the debt, declined an interview on the issue. 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 $5,000, 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 after 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 professional athletes, entertainers are, in some instances, 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 that sum (the total would actually 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.

Image Matt Martin of MNPublius, which highlighted a potentially embarrassing campaign matter of Senator Norm Colemans. Credit... Jessica Kourkounis for The New York Times

“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.”