Neo-Neocon has a great post on how difficult it can be to change political identities:

Many people wondered aloud why Zell Miller had not switched parties in light of his strong alignment with the Republicans and his staunch opposition to the Democrats. A "conservative Democrat" seemed to be a sort of oxymoron.

Miller's answer? That he was born into the Democratic Party and considers his party label to be "like a birthmark"--innate, and difficult to eradicate.

Miller's not the only one who feels that way in his neck of the woods:

"We're a little bit different than the Washington Democrats," said state Rep. Charles F. Jenkins (D-Blairsville), who represents Miller's home county of Towns as well as Rabun, Union and White counties. Jenkins said he understands why Miller refuses to join the Republican Party.

"You've got people up here who just will not switch from the Democratic Party because they've been Democrats since they were born," Jenkins said. "They're hard-headed mountain people. And hard-headed mountain people don't switch for anybody."

Well, most people are pretty hard-headed in that respect. But it's my impression that liberals may even be more hard-headed than most about changing their political identities.

That's because a liberal political identity tends to be so much more than a political identity--it's also a moral and personal identity. Liberals tend to equate their own position with such abstract (and non-political) qualities as goodness, kindness, lack of bigotry, intelligence--oh, a host of wonderful virtues. Any identity that is so identified is going to be particularly difficult to shed. Do some conservatives feel this way about their identity? Of course. But my impression is that it is a feeling even more basic to the political identities of liberals--at least the ones I know, and I know quite a few.

My sense is that this is one of the main reasons that my attempts to talk to my friends have so often been met with rage: to many of them, my espousing of any conservative causes means 1) I must be a bad (i.e.: selfish, racist, classist) person; and 2) if I ever were to convince them of the rightness of my arguments, they would be faced with leaving the fold, also, and becoming a bad person, too. Much better to let the whole edifice remain in place than to remove one little brick and risk the whole thing toppling down.

Similarly, in the comments to her post, several readers identify that for many on the left, politics is their religion, thus making a change in political worldviews almost as difficult as from changing from Catholicism to Judism--or vice versa. This also helps to explain much of the left's outright hostility towards traditional religious belief. As the recently deceased Hunter S. Thompson said in November to Sean Penn, immediately after the election, "I've got the worst possible news. Colorado has gone to hell like all the other states. They must have all voted the same way they pray." (Ironically, Dr. Gonzo's statement works for both sides of the aisle, of course.)

It also explains the two parties' difference in attitudes towards those who do switch, something that Glenn Reynolds observed a few years ago:

As the old saying has it, the left looks for heretics and the right looks for converts, and both find what they're looking for. The effect is no doubt subliminal, but people who treat you like crap are, over time, less persuasive than people who don't. If people on the Left are so unhappy about how many former allies are changing their views, perhaps they should examine how those allies are treated.