It’s the morning after in upstate New York, America’s new bellwether. In a traditionally conservative Congressional district, Democrat Kathy Hochul defeated Republican Jane Corwin. The 43 percent of the vote Corwin captured falls far shy of the 73 percent her Republican predecessor received in 2010.

The shorthand explanation for this precipitous drop is “Medicare.” Democratic attacks on the House Republicans’ budget, which includes a plan to reduce Medicare benefits for Americans under age 55, are credited with the party’s victory. The vagaries of local elections aside,that analysis is probably correct given trends in recent polling and the content of the advertising that dominated the campaign.

This would seem to give the Democrats a winning strategy for 2010: Rally around the seemingly awesome powers of preserving Medicare in its current unsustainable state.

Before attack plans are mapped, though, Democrats should consider this:Even before the election, some Republicans, including Massachusetts Senator Scott Brown, had begun distancing themselves from the aggressive cuts -- to both spending on the elderly and poor and to tax rates on the wealthy -- in the House Republican budget. Newt Gingrich went so far as to call the GOP plan a case of “right wing social engineering.”

If last night’s results spur a wider Republican shift -- bipartisan talks led by Vice President Joe Biden were already producing optimistic murmurs -- Democrats will face a choice. They can work to coax Republicans into a bipartisan deal that cuts spending and raises revenue, or they can gear up to use Medicare as a political club in 2012. The latter course might enable Democrats to retake the House; the former would extend to their opponents precisely the kind of political cover Republicans are probably seeking right now.

There are times when a party’s short-term self-interest is in perfect sync with the nation’s. For Democrats, this may not be one of them.

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