The American Medical Association announced its endorsement yesterday of a Democrat-led House plan to protect the rights of patients in managed-care plans and said it is joining other medical groups in a national ad campaign.

The decision by the AMA, made by its board this weekend in Chicago, was praised by President Clinton for sending "a strong message to Congress" that it is time to pass meaningful patients' rights legislation.

The legislation, sponsored by Reps. John D. Dingell (D-Mich.) and Charles Whitlow Norwood Jr. (R-Ga.), would ensure that people in health maintenance organizations have access to emergency room care and specialists and get doctor referrals outside their networks. It would allow lawsuits against HMOs that deny care.

"This bill delivers the essential protections patients and voters are demanding," said AMA President Thomas Reardon. "Doctors will be allowed to make medical decisions. Health plans will be held accountable for their actions."

The AMA said it was joining other groups, including the American Dental Association and the American College of Obstetricians and Gynecologists, in running newspaper ads in the districts of 28 House members in support of the Dingell-Norwood bill.

The insurance and HMO industries are lobbying hard against the legislation, contending it would drive up the costs of medical care significantly. The AMA attacked the insurance industry's stand as "irresponsible" and greedy.

The Senate passed a more restrictive GOP-written patients' rights bill in July after rejecting several Democratic provisions, including one that would have allowed patients harmed by medical decisions to sue their health plans. Clinton aides said he would veto the Senate bill.

In the House, Speaker J. Dennis Hastert (R-Ill.) tried unsuccessfully to unite his slim majority behind a GOP bill. Norwood, a dentist, and Rep. Tom Coburn (R-Okla.), a physician, demanded stronger legislation similar to that pushed by Democrats.

Earlier this month, after Norwood and Dingell introduced their plan, Hastert promised a vote on health care reform when Congress returns next month from recess. In a concession to supporters of expanded rights to sue, Hastert said the vehicle for that vote would be legislation being written by Coburn and Rep. John Shadegg (R-Ariz.) that is close to Dingell-Norwood on the lawsuit question.

The AMA commended Coburn and Shadegg for their efforts and said it would work with them and GOP leaders as legislation moves toward a vote.