Packer tries to understand why the GOP fringe is more powerful than the Democratic fringe:

The views of right-wing commentators in the grip of the paranoid style (Obama is a stealth radical, the Democrats are imposing socialism) are much closer to mainstream conservative and Republican belief than the views of their counterparts on the left (the levees in New Orleans were blown up by the government, the White House had something to do with 9/11) are to mainstream liberal and Democratic belief. The reasons are complex, but I would list these: the evangelical and occasionally messianic fervor that animates a part of the Republican base; the atmosphere of siege and the self-identification of conservatives as insurgents even when they monopolized political power; the influence of ideology over movement conservatives, and their deep hostility to compromise; the fact that modern conservatism has been a movement, which modern liberalism has not.