Gore and Bush, [Nader] said in an interview, "are both so marginal on the great issue of the distribution of power and wealth, and the corruption of cash register politics, that whatever real differences they are willing to fight for pale in comparison to the major subjects they are exactly on the same page on."
---WaPo, October 23, 2000 (source)
Almost everybody who voted for Nader in 2000 did so because they believed him when he said there was no difference between Gore and Bush. Noone would believe that today. Everyone on the left knows deep in thier hearts that the last four years would have been different had Gore been elected.
Therefore I don't believe that he'll get even half the votes he got four years ago.
If he needs Republican help to get on the ballot, then who is going to vote for him? Certainly not the greens.