Evan Bayh’s retirement announcement makes it more likely that Republican gains in the Senate could grow to as many as seven seats, but what I find interesting about the move is its total irrationality as a political decision. Any national ambitions Bayh might have once entertained are now absolutely finished. As acts of partisan disloyalty go, Bayh’s last-minute, surprise move is second only to those of Lieberman and actual party-switchers such as Specter, so he can forget about winning over Democratic primary voters in any future presidential elections. Unlike Dorgan’s retirement, Bayh’s departure is really entirely voluntary. Coats was potentially a serious challenger, but hardly an overwhelming favorite to win. If an incumbent with $13 million cash on hand isn’t safe in this environment when faced with opposition from a lobbyist for Bank of America, none of them is safe.

What this does do is re-confirm that national Democrats are very easily rattled, quickly intimidated and prone to pre-emptive political surrender. Dorgan’s retirement unsettled them, and Brown’s victory terrified them, and their irrational fear following last month is now costing them seats they could have otherwise held. Indeed, it is hard not to conclude that Bayh would not have retired had Brown lost in Massachusetts, which may mean that Brown is responsible for flipping two seats to the GOP. I don’t believe that Bayh retired because he was tired of the way things were being done in Washington. My guess is that he started to believe the other side’s propaganda that the country had turned against his party, and preferred to jump ship instead of spending most of this year in what he probably mistakenly regarded as a doomed cause.

As I was thinking about Bayh’s decision, I was reminded of the line from the TV adaptation of House of Cards when the PM sacks his party chairman in what is described as a “fit of pique or a fit of panic.” Bayh’s decision is a bit of both, and it is definitely a product of the national Democratic panic that set in over the last three weeks. The trouble for the majority now is that this panic will start to snowball as politicians in other basically safe-but-competitive seats begin to think that quitting is a better option. The GOP is still a long way from winning back control or either house, but it is receiving one unexpected gift after another courtesy of the administration’s tired “centrism” and “centrist” Democrats such as Bayh.