Even though the U.S. Senate is known as the best retirement home in America — great healthcare, plenty of daily activities, and people continue to pay attention to you for some reason — Virginia Sen. John Warner announced today that come next year, he’s out. And while his announcement is big news, even bigger is the fight that’s about to come to replace him.

Consider the circumstances. The commonwealth is a political toss-up these days. Sure, Republicans dominate Richmond, but folks looking to run for statewide office are more and more forced to appeal to the more liberal north, where both votes and money have congregated over the years. Even without the “macaca moment,” it wasn’t a huge surprise that Sen. Jim Webb defeated incumbent George Allen with the help of his Northern Virginia base.

On the Democratic side, former Governor Mark Warner could easily make another run for the seat, given his experience and popularity — things have changed plenty since his loss to John Warner in 1996. On the Republican side, well, things get complicated. Rep. Tom Davis has indicated he might run for the seat, as has former Governor Jim Gilmore. And here you have the fight for the two Virginia’s. Davis may be a Republican, but he’s a moderate one representing two Northern Virginia counties. Gilmore, on the other hand, has all the conservative credentials needed to win everywhere else. Should both run, we’ll see some interesting pandering as Davis tries to prove he’s a real conservative and Gilmore attempts to seem just a little more liberal.

And though it’s ridiculously early to make predictions, this is how we see things playing out. Davis jumps in early and spends most of 2008 on mock-up hunting trips and talking about how gay marriage is destroying America, killing puppies and fueling the Iraqi insurgency. In the meantime, Gilmore will campaign on a promise to widen I-66 to 12 lanes in each direction and eat at as many Peruvian places as it takes to convince Virginia’s growing Hispanic population that he’s one of them. Of course, Mark Warner will raise no money and simply run on name recognition, easily getting votes from Democrats while winning votes from Republicans who think he’s the older Warner.