Washington ? The White House is in serious discussions about legislation long opposed by many Republicans to guarantee that insurance for mental health disorders is as comprehensive as that offered for other illnesses.

A White House official said Thursday that President Bush planned to discuss “mental health parity” at an event Monday in New Mexico, home of Republican Sen. Pete Domenici, who has championed the cause for many years. It was unclear whether he would announce a legislative deal, endorse a set of principles or just discuss the issue in general terms.

The official, speaking on condition of anonymity, cautioned that no deal has been reached on legislation, which is sharply opposed by business groups for fear it would increase the cost of health insurance significantly.

House Majority Leader Dick Armey, who has opposed the legislation, is open to considering it, given the president’s interest, said Armey’s spokesman, Terry Holt. “He is willing to look at the president’s ideas on the issue, but like every other aspect of government, you’re going to have to set priorities,” Holt said.

Politically, the legislation would bolster the president’s “compassionate conservative” credentials and remove a potentially difficult campaign issue from his 2004 campaign.

“The signs are good from the White House, and we feel very optimistic,” said Allison Dobson, spokeswoman for Sen. Paul Wellstone, D-Minn., who has worked with Domenici on the issue.

Domenici said in a statement that a number of discussions have occurred among members of his staff and White House aides, but no deal has been reached on “substance or procedure.”