BRUNSWICK Maine (Reuters) - A federal appeals court on Monday rejected Maine's effort to trim some young people from its Medicaid rolls, saying the move would violate the Affordable Care Act. Maine Republican Governor Paul LePage, a critic of President Barack Obama's signature healthcare law, which is also known as Obamacare, had proposed in 2012 cutting non-disabled 19- and 20-year-olds from the state's Medicaid program to help balance the budget. A judge on the 1st U.S. Circuit Court of Appeals said on Monday the move would violate a key provision of the Affordable Care Act that forbids states from tightening Medicaid eligibility requirements for at least nine years. Chief Judge Sandra Lea Lynch wrote that the provision served "the legitimate purpose of ensuring that children do not lose health insurance as the country transitions from the pre-ACA Medicaid regime to the post-ACA Medicaid regime." Medicaid is a government health insurance program for low-income and disabled people. Maine is one of several states that have challenged Obamacare in court, and congressional Republicans, bolstered by big wins in midterm elections, have pledged to renew attacks on the law. "Today, judges have gone out of their way to defend the unpopular Obamacare law and obstruct the will of the public, made clear two weeks ago," Maine Department of Health and Human Services Commissioner Mary Mayhew said. She said welfare funds should be directed toward the "truly needy, not job-ready adults." Cutting the Medicaid rolls would have saved Maine $3.7 million, according to the LePage administration, which wants to slash $220 million in healthcare spending overall. (Editing by Richard Valdmanis and Peter Cooney)