But the drive for party unity has always carried costs too, and they seem to be growing in Bush's second term. By asking so few tough questions of Rove — and DeLay — congressional Republicans may be increasing their vulnerability to Democratic charges that the GOP is abusing its unified control over government to protect its own. "They really have become so arrogant that they don't think the rules apply to them," Democratic consultant Joe Lockhart says — an argument likely to headline many campaigns by Democrats next year. The emphasis on party cohesion also constricts Bush's maneuverability on issues....