Forty Senate Republicans have now joined their colleagues in the House to support Paul Ryan’s plan that would turn Medicare into vouchers that funnel money to private health insurers. They thumbed their nose at the special election in upstate New York earlier this week that delivered a victory to Democrat Kathy Hochul, who made the plan the focus of her upset victory.

So now it’s official. The 2012 campaign will be about the future of Medicare. (Yes, it will also be about jobs, but the Republicans haven’t come up with any credible ideas on that front, and the Democrats seem incapable of doing what needs to be done.)

This spells trouble for the GOP. Polls show an overwhelming majority of Americans — even a majority of Republican voters — want to preserve Medicare. They don’t want to turn it over to private insurers.

It would be one thing if Republicans had consistency on their side. At least then they could take the high road and claim their plan is a principled way to achieve the aims of Medicare through market-based mechanisms. (It isn’t, of course. It would end up squeezing seniors because it takes no account of the rising costs of health care.)

But they can’t even claim consistency. Remember, this was the same GOP that attacked the President’s health-reform plan in 2010 by warning it would lead to Medicare cuts.

Former President Bill Clinton counsels Democrats not to say Medicare is fine the way it is. He’s right. But instead of talking about Medicare as a problem to be fixed, Democrats should start talking about it as a potential solution to the challenge of rising health-care costs — as well as to our long-term budget problem.

Can we be clear about that budget problem? It’s not driven by Medicare. It’s driven by the same relentlessly soaring health-care costs that are pushing premiums through the roof and causing middle-class families to shell out more and more money for deductibles and co-payments.

Some features of Obama’s new healthcare law will slow the rise — insurance exchanges, for example, could give consumers clearer comparative information about what they’re getting for their insurance payments — but the law doesn’t go nearly far enough.

That’s why Democrats should be proposing that anyone be allowed to sign up for Medicare. Medicare is cheaper than private insurance because its administrative costs are so much lower, and it has vast economies of scale.

If Medicare were allowed to use its potential bargaining leverage over America’s hospitals, doctors, drug companies, and medical providers, it could drive down costs even further.

And it could force the nation’s broken health-care system to do something it must do but has resisted with a vengeance: Focus on healthy outcomes rather on costly inputs. If Medicare paid for results — not tests, procedures, drugs, and hospital stays, but results — it could give Americans better health at lower cost.

Let the GOP go after Medicare. That will do more to elect Democrats in 2012 than anything else. But it would be wise and politically astute for Democrats to go beyond just defending Medicare. Strengthen and build upon it. Use it to reform American health care and, not incidentally, rescue the federal budget.

Robert Reich

Robert Reich’s Blog