As much of a reputation Hollywood has for progressive, liberal, and leftist politics and activism, it's quite striking that the actor-politicians who have had actual, electoral success, have been, by and large, Republicans or conservatives. Ronald Reagan, governor of California and president, is, of course, the pre-eminent example, but there are secondary examples such as Clint Eastwood, one-time mayor of Carmel, California, Governor Schwarzenegger, the late Rep. Sonny Bono, and even one-time Governor Ventura of Minnesota. The only counter-example I could find was honorary "mayor" of Malibu, Martin Sheen, and could somebody tell me why a city with an actual, elected, mayor needed an unelected "honorary mayor" best known for intentionally courting arrest and incarceration at every protest compatible with his work-schedule?
Hollywood's reputation for leftism and leftish political activism is quite well-earned, and yet almost all the politicians produced by that culture have been on the right side of the dial. Why is that? Admittedly, a lot of the activism in the modern Hollywood left is aimed at electing other people to office - look at the swarms of has-beens and almost-about-to-have-beens like Whoopi Goldberg, Jeneane Garofalo, and Ben Affleck that buzzed about the Kerry campaign in the last season. Those folks are there to boost other candidates, rather than second careers of their own.
People like Alec Baldwin and Warren Beatty are always rumored to be getting into this or that, but it never pans out. For one thing, the rumors are always on a national scale - people were talking about Beatty in 2000 for the presidency. Yes, one could complain that to run for the presidency without ever having stood for even so much as the office of town dog-catcher, is deeply egotistical, but hey - that's never stopped Al Sharpton, Jesse Jackson, Sr., or any of the retired-military types who inevitably pop up in national election cycles. Nevertheless, the successful conservative or Republican actor-politician usually shoots for something more modest, like a house representative seat, or a governorship. The presidency awaits for those who prove themselves in a starter-seat, if the constitutional ban on immigrant presidential candidates doesn't otherwise conspire against said actor-politician.
There is the theory that a Republican or conservative bent in a denizen of a leftist utopia like Hollywood breeds practical political skills in the bearer; if the soil is deep enough and properly-fertilized with ambition, a second career as a politician can grow. The successful actor-politicians are by and large just that, politicians. Activism is often confused with politics on the left; it doesn't help that we refer to performance-artists, exhibitionist lunatics and serious party operators by that same, stupidly vague term. Though the marcher-protestor-puppeteer is an ineffectual buffoon who will never make a single change in the world worth the notice, and the party operator is making connections, quietly raising funds, organizing, building pragmatically for the long-term, both are called "activist". Not that you can't find the occasional buffoon or lunatic among the party operators - look to Kos for the refutation of that easy conclusion - but it's an essentially serious business. Meanwhile, the entertainer is naturally drawn to entertaining, if meaningless, nonsense, protest and street-theatre... I know, I know - too facile. I had this theory about Reagan's activism within the Screen Actors Guild, but look at this LA Weekly article about current SAG head Mike "B.J. Honeycutt" Ferrell's unwillingness to run for greater office... eh. That writer thinks the answer is "Democratic actors are cowards", which conflicts strangely with his touting of Ferrell's Marine service.