White House hopeful Newt Gingrich called the House Republican plan for Medicare "right-wing social engineering," injecting a discordant GOP voice into the party's efforts to reshape both entitlements and the broader budget debate. In the same interview Sunday, on NBC's "Meet the Press," Mr. Gingrich backed a requirement that all Americans buy health insurance, complicating a Republican line of attack on President Barack Obama's health law. The former House speaker's decision to stick with his previous support for an individual mandate comes days after former Massachusetts Gov. Mitt Romney defended the health revamp he championed as governor, which includes a...