It's hard for an extremist to get elected to any significant office. It's damn near impossible for an honest one.
It does happen, mind you. Roy Moore was elected as Chief Justice of the Alabama Supreme Court and may well be the next Governor of that state, horrifying as that may sound.
But generally, the extremists are left on the sidelines as the electorate gets larger, unless they disguise themselves as regular folk.
David Duke fooled a willing populace in a small part of Louisiana when he was elected to the State Senate, but was unable to fool the larger populace once he went statewide, losing a landslide to Louisiana's most famous felonious governor, Edwin Edwards.
George W. Bush only managed to become President--his buddies on the Supreme Court aside--by disguising his radical evangelism as "compassionate conservatism," aided and abetted by a pliant media.
But more often than not, idealogues max out at the House of Representatives. The electorate is still small enough, and these days, homogenous enough, to allow for the extremists to get into office. It's when they try to make the jump statewide--as Pat Toomey did in Pennsylvania--that they discover that their support is not quite as widespread as they had hoped.
So why bring this up? Well, it seems to me that the new dirty word in politics is "moderate." Arlen Specter, of whom I am no fan, was demonized by Toomey in the primary as being too moderate. It may end up costing him his seat in the long run, although it's too far out to really know if Hoeffel is going to catch him. Joe Lieberman will likely face a challenger from his left if he decides to run again in 2006 (although that would be a good thing in my opinion, since his "moderation" borders on appeasement).
But why the demonization? There are plenty of honorable moderates in both parties. John McCain. Olympia Snowe. Lincoln Chaffee. Tom Daschle. Hillary Clinton (don't believe the hype about how liberal she is). Mary Landrieu. And yet look what's happened to some of these people recently.
John McCain was mocked by the Speaker of the House--a member of his own party--when he dared suggest that perhaps tax cuts ought to take a back seat while we're at war. Tom Daschle--fighting a tough battle for re-election--has had to endure constant questions about his fitness as Minority Leader and potentially Majority Leader should the Democrats take the Senate back in November.
And of course, John Kerry endures constant sniping from the left in the form of Nader supporters because he's not, well, Nader.
But here's something that I think is important to remember. Nader--in his best year--has never gotten close to 10% of the national vote, and forget about actually earning an electoral vote. The last real third party threat was Ross Perot, and he garnered his support in 1992 by mounting a centrist challenge. Both Clinton and Bush chased Perot to the middle in that election, and still Perot took a significant chunk of the electorate.
The extremes are important in both parties. They push the boundaries of dialogue and ideas and are often the most vigorous part of the party. They look at issues in new and/or different ways and can affect the direction of the national discourse if they're good enough, much as the radicals in the Republican House of Representatives have done.
But there's a reason Dennis Kucinich never got any traction in the Presidential race, just like there's a reason neither Pat Buchanan nor Pat Robertson were a serious threat to George H. W. Bush. In order to win the big races, you have to appeal to the widest swath of the population. And the widest swath of the population isn't all that passionate about issues. They're moderate, for better or for worse.