Sen. Claire McCaskill (D) of Missouri was never going to have an easy time in her 2012 reelection battle. The first-term senator represents a Republican-leaning state that went (barely) for GOP presidential nominee John McCain in 2008 and has only gotten more Republican since then.

Enter “Air Claire,” the flap over an airplane owned jointly by Senator McCaskill, her husband, and a group of investors.

In the past two weeks, following press inquiries, McCaskill has paid more than $400,000 to both the federal government and St. Louis County to cover the cost of charter flights she took, plus back taxes and interest. The incident combines what she admits is negligence on her part regarding the back taxes with controversy over her use of the plane, which at a minimum had the appearance of impropriety.

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For McCaskill, an advocate for government ethics and transparency, the news has been devastating.

On Thursday, the nonpartisan Cook Political Report recategorized McCaskill’s reelection race from “lean Democrat” to “tossup.”

The airplane brouhaha “definitely makes things a heck of a lot harder for her,” says Jennifer Duffy, the Senate-watcher for Cook. “The biggest problem for her to overcome here is that it so undercuts the senator and the candidate she’s tried to be. From every angle, the optics are bad.”

Public money for private plane

McCaskill’s troubles began more than two weeks ago, when the website Politico began digging into public records on the plane, an eight-seat Pilatus PC 12/45 aircraft. Politico reported that she had spent “nearly $76,000 in public funds since 2007 to fly on a charter plane she co-owns with her husband and other investors.” Those flights had been paid for from McCaskill’s Senate office budget, which raised questions over whether she was using public money to subsidize the plane, Politico said.

While Senate rules do allow for the use of private aircraft for official business, McCaskill paid more than $88,000 to the US Treasury to cover those costs. Then it came out that at least one of the trips was to a political event, a violation of Senate rules. Republicans have filed a complaint with the Senate Ethics Committee.

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The story gets worse. This week, McCaskill revealed that property taxes on the plane had not been paid to St. Louis County for several years, to the tune of $287,000, plus an additional $32,000 in interest and penalties.

“There should have been a reporting to the county of the existence of this airplane,” McCaskill said in a conference call with reporters earlier this week. “There are people I could blame for this, but I know better. As an auditor, I know I should have checked for myself. I take full responsibility for the mistake.”

McCaskill was state auditor for Missouri from 1999 to 2007 – the springboard for her successful run for Senate in 2006. This week, she said she convinced her husband to sell the plane.

Possible opponents

One positive for McCaskill is that she does not face an A-list opponent on the Republican side. So far, two people have announced, and others are considering running. One contestant is former state Treasurer Sarah Steelman, who ran a weak campaign in 2008 when she ran for the GOP gubernatorial nomination. The other announced candidate is Ed Martin, who ran unsuccessfully for Congress in 2010. Considering campaigns are former Republican National Committee co-chair Ann Wagner and Rep. Todd Akin (R) of Missouri.

McCaskill has 20 months to recover, and she can only hope the worst is over. The Republican Party, and her eventual opponent, will certainly remind Missouri voters early and often about the plane all the way to Election Day.

But for now, McCaskill has done everything she can to put the issue behind her, says Darrell West, a political analyst at the Brookings Institution.

“As soon as [the plane issue] popped up, she dealt with it,” says Mr. West. “She paid the money, she acknowledged responsibility. But all those things don’t remove it as a campaign issue.”

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