Think about just how bizarre it is for Republicans to position themselves as the defenders of unrestricted Medicare spending. First of all, the modern G.O.P. considers itself the party of Ronald Reagan — and Reagan was a fierce opponent of Medicare’s creation, warning that it would destroy American freedom. (Honest.) In the 1990s, Newt Gingrich tried to force drastic cuts in Medicare financing. And in recent years, Republicans have repeatedly decried the growth in entitlement spending — growth that is largely driven by rising health care costs.