Dan Coats in an interview on Fred Thompson’s radio show explained his argument to the voters as to why Indiana Sen. Evan Bayh should not be re-elected:

“He talked a good game back at home, but when push came to shove, he was there with the liberals, there with Obama every time,” Coats said. On health care, Bayh was “catering to the liberals that he needed to cater to and he wasn’t listening to people in Indiana.”

Coats has a good deal of material to work with. Bayh voted for the stimulus, the Obama budget, and ObamaCare. He’s voted to confirm every nominee, from Sonia Sotomayor to the legal extremist Dawn Johnsen (for head of the Office of Legal Counsel) to Craig Becker for the National Labor Relations Board. He was a previous sponsor of card-check legislation, although he managed to stay noncommittal last year. In sum, Bayh was unwilling to oppose the liberal troika of Reid-Pelosi-Obama on a single meaningful domestic-policy item.

It is an argument that is likely to be repeated in states like Arkansas, Nevada, and Colorado, where challengers will make the case that the Democratic incumbent has facilitated the policies that voters back home oppose by large numbers. (In Colorado, for example, Michael Bennet is getting slammed by his opponent for his vote to confirm Becker: “Former Lt. Gov. Jane Norton, the Republican front-runner, said that while other Democrats were willing to buck President Obama’s choice, Bennet’s vote demonstrates he would provide ‘a rubber stamp’ for legislation commonly referred to as ‘card check.'”)

Recall that in Virginia, Bob McDonnell, running against a Democrat who had never cast a single vote in Congress in favor of an Obama agenda item, was able to win by a huge margin by making the case that Washington had strayed too far to the Left and that cap-and-trade, ObamaCare, card check, and takes hikes would be disastrous for his state’s economy. Scott Brown was able to make a similar argument against an opponent who similarly was not burdened by a congressional voting record in favor of the Obama agenda.

How much more effective will that argument be against Democratic incumbents like Bayh who are burdened not only by the “D” next to their name but also a voting record that fits the Republicans’ narrative? Incumbents like Bayh have a choice: start voting against the liberal agenda or hope voters lose their antipathy to the Reid-Pelosi-Obama agenda. The latter sounds like wishful thinking; the former will require a quick about-face. You can see why the Bayh seat and those of many other Democrats are now in play.