Both are pretty scary scenarios. Thing is, if this traitor loses the GOP primaries in August, he is going to turn round and vote for amnesty, cap and trade and all the rest of 0bama’s Marxist agenda, in a vicious temper tantrum, and to hit back at the conservatves that had dared to kick him out. On the other hand, even if he wins the GOP primaries in August, he'll probably still vote for all these 0bamabot bills anyways, because he'd have no primaries to worry about. So we might as well do everything we can to crush this persistent pain in the butt once and for all in August.
Difference between voting for (if he wins) and co-sponsoring the legislation (if he loses). ;)