Senate Republicans are preparing a legislative plan of action in case the Supreme Court strikes a major blow against ObamaCare and rules subsidies provided to people on the federal exchange are illegal. GOP senators are confident the justices will rule in their favor, and they want to be ready to act if millions of people lose their subsidies to buy insurance through the healthcare law. “If the Supreme Court were to say the law says what the law says, we would like to be ready with a response to that that makes practical sense for the 5 or 6 million...