Mitt Romney's choice of Rep. Paul Ryan as a running mate represents a dramatic departure from what had been widely taken, to this point, as Romney's basic theory of this election: That the key battle would be, as his advisor Kevin Madden once put it, "a referendum on the economy."
That theory produced a campaign whose key skill was deflection. Romney spent much of this year trying to turn the subject of the campaign back to the economy, and to pin the bulk of the blame for it on President Barack Obama.
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.
Obama has answered them with the traditional defense of the role of government in providing for citizens in need, and with the conventional wisdom among Democrats that giant entitlements need to be tweaked, rather than revolutionized. Obama has also made clear, in elevating Ryan and picking public fights with him, that he believes the old rules of politics apply: that tinkering with entitlements (if only for those who haven't yet retired) is poison in, in particular, the key state of Florida.
Romney, long a technocrat and a moderate, now appears to have embraced the Republican Party's own new political bet: That the old rules are off; that Americans are panicked about the size of government and ready for a fresh and radical new vision.
And an election that was expected to be a referendum on the incumbent president looks like it may be a referendum on a 42-year old congressman from Janesville, Wisconsin.