Are would-be running mates John McCain and Joe Lieberman turning into rivals? CQ Politics reports that that the wildcard politicians—one a "notorious party turncoat," the other the OG "maverick"—have already sparred twice on the Senate floor this year. During yesterday's debate on the DC Voting Bill, McCain raised a point of order challenging the constitutionality of the bill, a rare and bold move by Senate standards. "I have very little doubt that this legislation before us violates the Constitution," McCain said. Lieberman directed his balance-of-power response at McCain: "Even if you feel that this legislation may be unconstitutional, we're a legislative body," not the Supreme Court. While McCain criticizes Obama for failing on bipartisanship, Lieberman praises Republican dissenters: "I've been in that position," the Connecticuter said, referring to breaking from one's party. "It's not fun. It's lonely."