(MCT) — WASHINGTON — Less than a year before Americans will be required to have insurance under President Barack Obama’s health-care law, many of its backers are growing increasingly anxious that premiums could jump, driven up by the legislation itself.

Higher premiums could undermine a core promise of the Affordable Care Act: to make basic health protections available to all Americans for the first time. Major rate increases also threaten to cause a backlash just as the law is supposed to deliver many key benefits Obama promised when he signed it in 2010.