Both political parties are proposing to cut the $500 billion-a-year healthcare program for the elderly. They disagree as to how. Republicans want to rely on the marketplace, saying competition can be harnessed to drive down costs. Democrats say a panel of experts, created in the Obama administration's 2010 healthcare overhaul, should decide how to wring savings from the program. The fight takes center stage as the U.S. House considers a budget resolution endorsing Republicans' vision for the half- century-old program. It probably will win adoption today after lawmakers dispense with some competing budget proposals, including one modeled on the deficit plan recommended by the leaders of President Barack Obama's debt-reduction commission.