Marc provides a guide to its meaning:
Should Republicans have reason to crow about their chances in 2010? On the one hand, there’s no Bush on the ticket. Ok, there might be one, but he’ll be in Florida, and besides, he’s not THAT Bush. Two: the Democrats are in charge, and Republicans will have something to rally the base with. Three: … three is a "but." But… more Republican retirements are expected, including at least two in blue states (Chuck Grassley of Iowa and George Voinovich of Ohio.)
The Dish 