Since Republican presidential nominee Mitt Romney named Congressman Paul Ryan as his running mate, the focus of the U.S. presidential campaign has shifted rapidly from the economy to Medicare.
Mr. Ryan's plan to give future seniors the option of accepting a fixed government subsidy to buy private health insurance, to rein in overall costs, has given President Barack Obama breathing space to avoid talking about his own economic record.
The Republican right is convinced voters will reward the Romney-Ryan ticket for taking on the biggest issue at the heart of the U.S. fiscal time bomb. Others in the party are worried Mr. Romney has ceded the election to Mr. Obama, and dozens of Republican seats in Congress to the Democrats, by raising the unpopular prospect of Medicare reform.
Indeed, Mr. Obama has spent the week on the campaign trail attacking the Romney-Ryan plan to "end Medicare as we know it." And a raft of new attack ads by Democratic candidates for Congress seize on the Ryan budget plan, which was adopted by the Republican-led House of Representatives.
All that is giving some Republicans pause about the wisdom of the Ryan pick.
The nervous are being dismissed as "Beltway bed-wetters" by the Wall Street Journal and other conservative opinion makers. But a couple of new polls suggest there is reason to question the wisdom of Mr. Romney's choice of Mr. Ryan.
First, a Gallup survey released Thursday shows that Mr. Obama continues to get dangerously low marks from voters on his handling of the economy.
Only 36 per cent of Americans approve of Mr. Obama's economic management, while 60 per cent disapprove. That is the lowest rating for an incumbent since George H.W. Bush sought re-election in 1992 – and he lost. Mr. Bush's score was a miserable 18 per cent.
Bill Clinton is largely seen to have won the 1992 election by keeping a laser focus on the economy. "It's the economy, stupid" was the unofficial slogan of his campaign.
Had Mr. Romney adopted a similar game plan – for instance, by picking an uncontroversial running mate – he might have been able to adopt a similar tactic.
This week, however, the main topic on the campaign trail is Medicare. Americans are being inundated with claims from both sides about what would happen to the government-run health program for seniors under a Republican administration.
On the face of it, that seems like a risky strategy for Mr. Romney. Polls taken over the past couple of years show a strong majority of Americans want to preserve Medicare in its current form. On the other hand, they concede the program is on shaky fiscal ground.
Mr. Romney has insisted he will propose his own plan to balance the budget and reform so-called entitlement programs. But an outline released earlier this year embraces aspects of the Ryan plan to turn Medicare into a voucher scheme for Americans currently under 55. They could also stick with the public plan, but there is no guarantee (from any candidate) that it would remain as generous for future seniors as it is for current ones.
In South Carolina on Thursday, Mr. Romney used a white board as a prop in an ad hoc news conference to explain the differences between his Medicare plan and Mr. Obama's.
The President's health-care law cuts $716-billion (U.S.) from Medicare between 2013 and 2022. Mr. Romney said he would restore those cuts but make changes to the program for those who turn 65 starting in 2022, in order to keep Medicare solvent.
"Under the President's plan, Medicare would go bankrupt," Mr. Romney added.
The choice of Mr. Ryan, the party's leading budget hawk, suggests the GOP nominee is more concerned about maximizing turnout among the Republican base and Tea Party movement than wooing voters who are still on the fence.
One reason for that is the historically low number of undecided voters in this election.
For instance, a Purple Strategies poll released Thursday showed that only 5 per cent of Florida voters remain unsure about whom they intend to vote for in November. Only 7 per cent of those who have decided said they could change their minds by then.
The situation is similar in other swing states that are critical in determining the election outcome: Ohio, Colorado and Virginia.
The Purple Strategies poll, which has a margin of error of plus or minus four percentage points in each state, suggests Mr. Romney has failed to get the big bounce from picking Mr. Ryan that John McCain got right after he picked Sarah Palin in 2008.
But the survey by the bipartisan polling firm suggests the race has tightened up in recent days. Mr. Romney has razor thin leads in Florida, Ohio and Virginia, while Mr. Obama has a three percentage point advance in Colorado.
The question is whether the emergence of Medicare reform as a central campaign issue will drive Democrats – and those who lean Democratic – to the polls in greater numbers than Republicans and their sympathizers. Mr. Romney has taken a gamble in that regard.