Forget Social Security. Medicare just might be the new Third Rail of American politics. In the mid-1990s, then-House Speaker Newt Gingrich pushed for $270 billion in Medicare savings. He got a government shutdown and contributed to President Clinton's reelection in 1996. Last year, Democrats passed a healthcare bill that cut $500 billion from Medicare, and senior citizens issued a strong rebuke in the 2010 election, swinging about 20 points towards Republicans. And now, Republicans have lost a special election in western New York and are worried that they might be putting their 2012 prospects in jeopardy with an ambitious proposal to turn Medicare into a voucher program. Medicare is the entitlement where the parties are actually trying something, and so far, they're getting burned by the new Third Rail.