WASHINGTON — A Supreme Court ruling due in a few weeks could wipe out health insurance for millions of people covered by President Barack Obama’s health-care law. But it’s Republicans — not White House officials — who have been talking about damage control.A likely reason: 26 of the 34 states that would be most affected by the ruling have Republican governors, and 22 of the 24 GOP Senate seats up in 2016 are in those states.Obama’s law offers subsidized private insurance to people …