Sidney Blumenthal, a former senior adviser to President Bill Clinton and strategist for Hillary Clinton’s Democratic presidential campaign, went “off message” (his words) today with a warning to his party: Don’t run against GOP nominee John McCain by painting him as Bush III, because he’s not. Bucking the Democratic National Committee’s talking points that characterize a potential McCain administration as tantamount to a third Bush term, Blumenthal told our Liz Halloran that running on that strategy in the fall would be a mistake. “I understand people’s political reasons for doing that,” he said. “I think it’s more helpful to describe [political opponents] as they are.” Bottom line, Blumenthal calls the strategy “a mistake and adds: “The public doesn’t see [McCain] that way. That’s a hard sell.” At an event to promote his new book, The Strange Death of Republican America: Chronicles of a Collapsing Party, Blumenthal also predicted that McCain has “lots of room to maneuver” politically before the fall election. What hurts the presumed Republican nominee? His need, Blumenthal says, to reassure conservative Republicans about the kind of nominees he’d make to the Supreme Court.