I can't shake the feeling that he might pull a Jim Jeffords. Maybe because he's publicly toyed with the idea of switching parties. If he wins, I'd put him in the ? column until further notice.
He will cross the aisle if he finds himself as the tie breaker or in the minority.
Chafee is and will always be a RINO, but considering the fact that Liddy Dole, Karl Rove and Ken Mehlman have pumped millions into his campaign I doubt he'd ever switch. He'd rather be a thorn in our side in the same mold as Snowe, Collins, DeWine, Graham and McCain (probably without DeWine after 11/7).