Give Claire McCaskill some credit for agreeing to discuss her legal issues on the air with Jamie Allman today in St. Louis. Most politicians facing potential charges for tax evasion would clam up, advisedly, to ensure that they don’t provide contradictory public statements for a potential prosecution. McCaskill has already pledged to pay whatever she owes, so that probably won’t be an issue anyway — and besides, her political career is dead unless she can convince the Show-Me State that she was just incompetent and not crooked.

And McCaskill deserves credit for taking blame at every turn in this interview, and answering all of Allman’s questions rather than attempting to duck them.  McCaskill stumbles while being a little too honest when Allman asks whether McCaskill can assure voters that everything she’s doing now is legal. She also appears to balk at releasing the tax records for the corporations involved:

McCaskill tries to deflect questions about the tax records by claiming that her husband’s success has been a “bright shiny object” for her political opponents, but that’s hardly responsive to the question. She used her husband’s success to the extent that she used the plane, and contributed to it to the extent that she transferred $76,000 from her Senate budget to the company that owns the plane. Had the money come from her campaign coffers rather than her Senate budget, it wouldn’t have been as much of a problem for the reason McCaskill gives regarding Obama’s use of the plane; either campaigns have to pay to use transportation or the companies providing it have to declare an in-kind contribution.

Meanwhile, one Republican opponent has already rolled out a new web ad on the scandal. Sarah Steelman uses McCaskill’s own words to argue that Missouri voters should never vote for McCaskill again. This one will leave a big mark:

McCaskill’s doing just about everything she can for damage control, including reaching out to Missouri talk-show hosts to express her mortification and her regret, but this is a lot of damage to undo. Don’t be surprised if Democrats end up with Robin Carnahan back on the ticket in 2012.