In some senses, yes; obviously, individuals can be. As a matter of practical national politics, though, Dick Morris says “No,” and he has history to back him up. Barack Obama may be moving to the center now, but if he wins in November, the Democratic leadership in Congress will pull him back to his hard-left primary positions, just as they pulled Bill Clinton hard left after his election; and the same sort of thing will happen to all those moderate Democrats the party’s raised up to run in conservative House districts around the country. Whatever their personal positions, they’ll either be reliable votes for the Democratic leadership or they’ll be marginalized right out of Congress. Which is to say, on the national level, there’s really no such thing as a moderate Democrat: whatever they say now, when it comes down to votes, they’ll vote with Nancy Pelosi.
I hear people talk about RINOs (Republican In Name Only) who are presumably trying to be moderate Republicans and are therefore judged as not true Republicans by those further to the right. Do Republicans not marginalize those of their party who do not follow the party line in the same way Democrats do?
Yes and no. The thing is, RINOs (to use the term coined by conservatives) are in fact a large chunk of the party establishment and leadership–Arlen Specter would be a particularly good example. When marginalization takes place, it tends to be of the conservative wing of the party.
Would you really say that Clinton was “hard left”? I think of him as a quintessential centrist, actually. But, again, the view here is from my own odd place in our divided politics.
Clinton was unquestionably a centrist. The point is that in 1993-94, he had to govern left in order to stay in line with his Congress. Oddly enough, the “Republican Revolution” may have been the best thing that happened to his presidency–it enabled him to reclaim the center.