Kevin Drum is an optimist:

But in the longer term I think the tea party movement is more dangerous to Republicans than he lets on. There’s a limit to how crazy a party can get and still win elections even occasionally, and the tea partiers are very rapidly taking the GOP to that point and beyond. It’s probably a net benefit in 2010 — though even that’s debatable — but beyond that I suspect it’s almost pure millstone.

Drum says he has an article on this coming out for the print Mother Jones soon, so I’ll be interested to see it. But I think he’s probably wrong. The research I’ve seen offers very little support for this thesis. The price of being perceived as ideologically extreme is really pretty low. When you consider that Bill Clinton won Pennsylvania twice, then Al Gore won it, then John Kerry won it, and then Barack Obama won it by a hefty 54–44 margin. So I see no real reason to think it’s fertile ground for Pat Toomey’s brand of Club for Growth ideological extremism. But Toomey’s doing okay in the polls and if we have two more months of job losses he’ll probably win.

If there’s a problem with your party being “too crazy” it’s that you may govern poorly leading people to get sick of you and kick you out. I think that’s basically what happened in 2006 and 2008. But there are plenty of other ways for this to happen. Jimmy Carter presided over a party that was basically too ideologically incoherent to govern effectively even though his administration actually presided over a lot of underrated good initiatives with long term (and at times delicious) consequences. Barack Obama is being hamstrung not by “crazies” in his party, but by moderates who were too timid when he was politically strong and an opposition that’s not-at-all-timid in obstructing his administration’s recovery initiatives now that he’s weak.