WASHINGTON — A key House subcommittee yesterday cleared Rep. Patrick J. Kennedy’s signature legislation to put insurance coverage of mental illness on an equal footing with that of physical ailments, bringing the bill a step closer to what Democrats and Republicans said is a likely presidential signing ceremony this fall.

“I think there is a determination by the leadership in both houses of Congress to get mental-health parity enacted before adjournment this year,” said Rep. Frank Pallone, D-N.J., chairman of the health subcommittee of the House Energy and Commerce Committee, which passed the measure on a voice vote.

The full committee is slated next week to clear the measure for action on the House floor. The measure already enjoys the support of a bipartisan House majority.

If the House passes the mental-health bill, compromise negotiations would ensue with the Senate, which passed its version without opposition last month. The chief Senate sponsors are Sen. Edward M. Kennedy, D-Mass. — Representative Kennedy’s father — and Senators Pete V. Domenici of New Mexico and Mike Enzi of Wyoming, both Republicans.

While he has not endorsed either bill, President Bush has expressed support for equal medical-insurance treatment of mental and physical illnesses, so backers of both versions are optimistic that he will sign an eventual compromise.

Nevertheless, some spirited fights lie ahead on the details of the legislation, as yesterday’s subcommittee debate confirmed.

“I don’t want to get involved in these interfamily disputes between Congressman Kennedy and Senator Kennedy,” Pallone joked at one point as the younger Kennedy — not a member of the health subcommittee — quietly buttonholed members of the panel to argue against amendments that would have made his House bill more like the one his father has steered through the Senate.

Republicans argued yesterday that the House bill, co-sponsored by Rep. Jim Ramstad, R-Minn., would impose unnecessary costs on insurers and perhaps even drive some to drop mental-health insurance altogether.

Supporters of the Kennedy-Ramstad bill replied that the worries about cost inflation are overblown. On a 19-to-9 vote, generally along party lines, the Republicans failed to amend the measure to bring it closer to the Senate version, which enjoys the support of the business community.

Both versions of the bill aim to get sufferers of mental illness — including alcohol and drug addiction — medical treatment that is equal to what sufferers of physical illnesses enjoy. Currently, the treatment of mental illness tends to be subject to limits not applied to heart disease or other physical illnesses. For example, many plans permit fewer physician visits for mental-health patients, or levy higher co-payments and other fees in certain circumstances.

The mental-health parity bills include no flat requirement to cover mental illness. Rather, the bills specify that if an insurance plan offers any coverage of mental illness — as most have gradually come to do in recent years — it must generally provide the same range of coverage, with comparable fees, that it provides for the treatment of physical sickness or injury.

Supporters of the Senate version have long argued that it better accommodates the realities of the marketplace, particularly the need to hold down medical costs. At the political level, they argue that the House version cannot become law because it will drive away the support of large insurance companies and business groups that prefer the Kennedy-Domenici-Enzi bill.

They argue that the House version is far too specific in its rules for mental-illness coverage. One major example: the Kennedy-Ramstad bill uses the mental-health industry’s standard list of medical illnesses to prescribe what ailments must be covered.

Several Republicans criticized the coverage list for including such conditions as jet lag and caffeine addiction.

Republicans warned that some companies might opt out of mental-health coverage altogether, rather than accept the House bill’s mandatory-coverage list of illnesses.

But Pennsylvania Rep. Timothy Murphy, one of the Republican backers of the Kennedy-Ramstad bill, said it is proper for diagnosticians to screen patients for such conditions as jet lag. Murphy noted that some of its symptoms — mood swings, inappropriate sleep patterns — could fit more dangerous conditions.

The Senate also answered business concerns by exempting companies with fewer than 50 employees from the parity bill’s mandate and by making the bill take effect a year after it is signed into law.

jmulligan@belo-dc.com