By ROBERT PEAR, New York Times

WASHINGTON — Congress on Tuesday moved close to final approval of a bill that would require group health insurance plans to provide more generous coverage for treatment of mental illnesses, comparable to what they already provide for physical illnesses.

The Senate approved the legislation as part of a tax bill promoting the use of alternative fuels, including wind and solar power. The bill, passed by a vote of 93 to 2, would extend expiring tax breaks, and create a variety of new ones, for energy conservation and the use of renewable energy sources.

The House, by a vote of 376 to 47, passed the mental health measure as a free-standing bill. The two chambers agree on the substance of the legislation, which requires equivalence, or parity, in the coverage of mental and physical ailments. Federal law now allows insurers to discriminate, and many do so, by setting higher co-payments or stricter limits on mental health benefits.

President Bush, business groups, insurance companies and mental health advocates all support the measure.

Although the House and the Senate are using different vehicles for the legislation, supporters said that a single mental health bill would soon emerge from Congress and go to Mr. Bush for his signature.

The mental health bill was a top priority for Senator Paul Wellstone, the Minnesota Democrat killed in a plane crash in 2002. It is also a major goal for Senators Pete V. Domenici, a New Mexico Republican who is retiring after 36 years in Congress, and Edward M. Kennedy, Democrat of Massachusetts, who followed the vote from his home in Hyannis Port, where he is recovering from treatment for brain cancer.

“This bill provides mental health parity for about 113 million Americans who work for employers with 50 employees or more,” said Mr. Domenici, who has a daughter with schizophrenia. “No longer will people with mental illness have their mental health coverage treated differently than their coverage for other illnesses like cancer, heart disease and diabetes.”

With this bill, said Senator Amy Klobuchar, Democrat of Minnesota, “we are eliminating the stigma and affirming the dignity” of people with mental illness.

Senator Christopher J. Dodd, Democrat of Connecticut, said, “Mental illness will no longer take a back seat to physical illness.”

Under a 1996 law, health plans were forbidden to set annual or lifetime dollar limits on mental health care that were lower than the limits for other services. But insurers have gotten around the law by charging higher co-payments and setting stricter limits for mental health services.

For example, insurers often refuse to cover more than 20 visits a year to a psychotherapist. And a patient may have to pay 20 percent of the cost for visiting a cancer specialist, but 40 percent or more for a mental health specialist.

Under the bill, if a group health plan covers the treatment of mental illness or drug or alcohol abuse, the treatment limits and financial requirements for these services can be “no more restrictive” than those that apply to medical and surgical benefits.

What this means, the bill says, is that co-payments, deductibles and out-of-pocket expenses for mental health services cannot be higher than those for treatment of physical illnesses.

E. Neil Trautwein, a vice president of the National Retail Federation, a trade group, said: “We strongly support this compromise bill. Employers know that mental health issues can hamper the productivity of workers. The bill allows employers to determine the scope of mental health benefits, to manage the benefits and to work out treatment plans and protocols for individuals.”