HUNTINGTON, W.Va. — Inside the sleek hillside headquarters of Valley Health Systems, built with a grant from the health care law, two employees played an advertisement they had helped produce to promote the law’s insurance coverage for young, working-class West Virginians.

The ads ran just over 100 times during the recent six-month enrollment period. But three conservative groups ran 12 times as many, to oppose the law and the local Democratic congressman who voted for it.

This is a disparity with consequences. Health professionals, state officials, social workers, insurance agents and others trying to make the law work for uninsured Americans say the partisan divisions and attack ads have depressed participation in some places. They say the law has been stigmatized for many who could benefit from it, especially in conservative states like West Virginia that have the poorest, most medically underserved populations but where President Obama and his signature initiative are hugely unpopular.

Steven L. Shattls, chief executive of Valley Health, a network of 28 health centers, said his organization would like to rerun its ad before November, when enrollment resumes. But he also conceded, “We have limited resources.”