Senate Majority Leader Harry Reid called a vote on Representative Paul Ryan's Medicare plan Wednesday, forcing lawmakers to take sides on what has become a defining issue for the 2012 campaign.  The vote comes one day after Democrat Kathy Hochul's upset victory in New York's heavily Republican 26th Congressional District. The vote was seen as a chance to test the air on Medicare reform, and Hochul's victory made one thing clear: the winds have changed. Jennifer  Steinhauer, congressional correspondent for The New York Times, says that with an election year on the horizon, Democrats are using the opportunity to puff up their sails –  while some Republicans are scrambling to change tack.