Senators say they are closing a loophole in a federal law meant to force insurers to cover mental health conditions as they would any other medical problem.

Sens. Paul Wellstone, D-Minn., and Pete Domenici, R-N.M., want to update a 1996 bill that is set to expire this fall. The act's flaw, the senators said, is that it dictates equal footing only for annual and lifetime benefits provided patients. The new fix would prevent health plans from limiting hospital stays and doctors' visits for treatment of mental health symptoms.

"The big problem was that people were cut off from the very beginning, so how much you spent in a year or in a lifetime was beside the point," Wellstone said in a recent interview.

The legislation does not require companies to offer mental health coverage as part of employee health benefits. Instead, companies that do must provide the same level of coverage for mental health as they do for physical health, from routine checkups to major surgery. Insurers would have to charge the same co-payments and deductibles for either types of conditions, whether influenza or schizophrenia.

Sponsors said the original legislation was not as expansive because of political considerations. The Senate Health, Labor and Pensions Committee is set to vote on the new, expanded version of the law Wednesday; supporters expected it to head for a full Senate vote by the end of the session.

But Sen. Judd Gregg, R-N.H., has expressed strong opposition to the bill, saying Senate leaders were not allowing other voices to be heard.

Advocates have argued the human brain, as important as any other organ, should treated as such.

"Current law is at best a partial parity that leaves many people vulnerable to inferior insurance coverage," said Ralph Ibson, a lobbyist with the National Mental Health Association.

The Surgeon General's Office has said mental disorders affect almost one in five Americans. Two-thirds never seek treatment, including even people with severe mental illness.

Health plans and employers who provide insurance coverage contend the plan amounts to a mandate from the Washington.

James Klein, president of American Benefits Council, said the plan would cause some employers to drop mental health coverage altogether. The council represents large employers who provide health coverage to workers.

Klein said the new mental health parity plan "would be one of the most restrictive and intrusive requirements ever imposed by Congress on the health benefits voluntarily offered by employers to their employees."

Backers insist that increasing patients' mental health coverage will save money that is now lost to lost decreased productivity and wages. Congressional budget analysts estimated that the new plan would raise insurance premiums for individuals by 1 percent each year.

The mental health association's Ibson said rates have not risen beyond workers' means in the more than 30 states that have passed mental health parity laws.

The new plan has its drawbacks, say supporters and advocates. The Senate version does not cover equal coverage for substance abuse treatments.

"You have even more stigma in this area," said Wellstone, who promised to back future legislation. "You don't have the same people, families stepping forward with the same kind of full force. We need more of that."

A House plan would add substance abuse treatments to an overall mental health parity bill; leaders there have not scheduled a debate on the bill.