Would Ben Nelson switch parties?

And, along with that, would Lieberman switch caucuses? In his latest post at 538, Nate Silver gives the GOP about 50-50 odds of getting its Senator count up to 49, and suggests that, should that be the case, its charm offense on those two senators will start soon.

Let's take Nate one farther. What are the odds of those two events happening?

First, on Nelson. I think he might be as much as 60-40 in favor of it, UNLESS he's not going to run for re-election himself, in which case he might punt that down the road. Lieberman? Given how much a weather vane he can be, I'd put the odds anywhere from as low as 20 percent to as high as 80 percent. That said, with him on abortion, especially, will tea partier types fight back against this idea?

And, if Nelson is convertable, is there any other senator other than Lieberman that could be persuaded to switch? I really can't think of one.

So, if the scenario played out this way, would the GOP approach both at the same time? Nelson first? Lieberman first?