LOUISVILLE, Ky. — The next Congress will begin work immediately next year toward repealing President Barack Obama’s health care law but delay the changes as Republicans try to come up with an alternative, Senate Majority Leader Mitch McConnell said Saturday. The Kentucky Republican insisted that some 20 million Americans who have health care through the six-year-old law will not lose coverage, though the likely upheaval in the insurance industry suggests many could. Asked about the Senate’s timetable to scrap the law, McConnell said: “We’re going to move to it after we go back in the first week in January.” But during a speech in his hometown of Louisville, the senator cautioned patience from the law’s critics as Republicans create an alternative. “You can’t just snap your fingers and go from where we are today to where we’re headed,” McConnell told a crowd at the Kentucky Farm Bureau’s annual meeting.