The presidential campaign has proven too intense, however, to allow a major party candidate to run as a cipher. And as Romney has lost traction on Obama while seeing his own character and policy defined by Democrats, he has chosen a dramatically different tack.

The election is now a choice, not a referendum, a contest between two clearly and sharply different policy visions and views on the role of government.

Ryan’s policy views are as clear as Romney’s are vague and complex, aimed not just at cutting spending but at rearranging Americans’ relationships with the federal government. His budget plan bets that turning Medicare into a voucher would stop swelling health care costs and hands anti-poverty programs to the states. He has backed — though the most recent budget does not — a version of President George W. Bush’s politically disastrous attempt to shift Americans’ retirement from Social Security guarantees into private investments.