Actually, there's a danger there. The Democrats are on the verge of a split between their far left-wing and more moderate members. They've started to feud on Iraq, but even before that you saw the feud in the defeat of Cynthia McKinney in the Democratic Primary.
If there is a split, after 2004 -- and I'd say that's slightly better than a 50-50 proposition right now -- that would most likely result in a significant number of Dems joining the Greens. The Dems then would no longer have to kowtow to the left and could embrace a vigorous defense policy and a somewhat less radically left economic policy.
If this were to happen and the Republican Right managed a purge along social lines, the socially libertarian Republicans, like myself, might well find the Dems a more palatable party to belong to and vote for.
If this happens, I'd figure the Greens would have about a sixth of the voters, the GOP would hold about a third, and the Democrats would hold a plurality, if not an absolute majority, with about half the votes.
I'd say this scenario is unlikely, but I'd say it has a one-in-five chance of happening. More likely -- and better, in my opinion -- the GOP will find a way to hold all us bickerers and be a 55-60% party for the foreseeable future.
Ultimately, the GOP needs to gather up some testosterone and tell the Religious Right that it can have a certain amount of bully-pulput support for personal restraint, but no police compulsion in suport of its preferences.
They really can't get a better deal than that. The Democrats will enlist police compulsion against their preferences, the significant third parties (Libertarians and Greens) will offer the same two choices, and attempts to organize third parties more to the liking of the Religious Right have been pathetic failures even by third-party standards.