WASHINGTON — In one sense, the late autumn interlude in the Oval Office was one more heartening proof that politics makes for strange bedfellows — “a perfect example,” in Rep. Patrick J. Kennedy’s words, “of everybody coming together for a happy ending.”

But yesterday’s muted commemoration of a landmark mental-health bill held an element of the bittersweet as well. President Bush welcomed a couple — Republican Sen. Pete V. Domenici of New Mexico and his wife, Nancy — drawn long ago to the cause by the heartbreak of their daughter Clare’s schizophrenia.

Two others in the room, Rhode Island Democrat Kennedy and his friend Jim Ramstad, a Republican congressman from Minnesota, knew the horrors of addiction from humbling personal experience.

Then there were the two men who have faced demons of their own in years gone by and who today, in different ways, are nearing the end of their time on the public stage. Sen. Edward M. Kennedy, the Massachusetts Democrat who is Patrick’s father, is gearing up for another long campaign to enact sweeping health-care reform, but he has only recently returned to work after long treatment for cancer of the brain. Mr. Bush is concluding a difficult and divisive eight years as president, without very many bipartisan victories as clear-cut as the one he celebrated with the four lawmakers yesterday.

Still, celebrate they did for half an hour or so, the elder Kennedy leaning on the cane his father once carried, Mr. Bush presiding at the glossy-topped wooden desk where the senator’s brother, John F. Kennedy, once sat as president, his young son and namesake playing at his knee.

“This is the most famous desk that any president ever used,” Patrick Kennedy quoted Mr. Bush as telling him and his father, “primarily because your brother, your uncle, was behind the desk when John-John crawled out.”

The politicians talked baseball — Senator Kennedy and Mr. Bush as serious fans, and Domenici as a onetime professional ballplayer with serious prospects. They laughed. They spoke of policies they had pursued together, omitting mention of the mighty battles that have divided some of them these past eight years.

Mr. Bush engaged the legislators on the details of their long struggle for mental health parity — the requirement that mental illness, including alcoholism and drug addiction, be insured on a par with the coverage for physical illness and injury.

The president told Senator Kennedy how well he looked and saluted Domenici and Ramstad — both retiring at the end of the 110th Congress — on their careers.

At length, Mr. Bush gathered the four legislators around the desk as he signed “a beautifully leather-bound” print of the bill, Patrick Kennedy recalled after the private meeting. It was a ceremonial act; the bill actually became law on Oct. 3, as a last-minute amendment to the $700-billion rescue bill for the nation’s financial system. Rather than sign the measure with the customary handful of pens to be dispensed to his guests as mementos, Mr. Bush explained that he was purposely affixing his signature to the bill with a single pen.

“This is going to be one of my most historic bills,” Mr. Bush said, according to the younger Kennedy. “This pen is going to go into my presidential library.”

Patrick Kennedy said he was moved by the president’s “very gracious” gestures and remarks. He said Mr. Bush’s quiet celebration with the lawmakers underlined “the significance of this piece of legislation as the historic civil rights bill that it is.”

“This means that 113 million Americans will now have access to equitable treatment for mental illness,” Ramstad said after the White House ceremony. The new coverage of addiction is a point of pride for Patrick Kennedy, who has been in recovery since an automobile accident prompted him to seek treatment for his abuse of prescription medicine and alcohol in May 2006.

Ramstad, a recovering alcoholic for more than 25 years, has guided Kennedy in recovery. Together, they campaigned in congressional hearings across the country for the parity legislation.

Senator Kennedy indulged at one point during the meeting in some of his customary joshing of his “upstart” son. Then Patrick Kennedy told the president in a light-hearted vein that his job must be especially tough for those who arrive in the Oval Office with “big shoes to fill” — an allusion to Mr. Bush’s father, former President George H.W. Bush.

“Boy, don’t I know it,” Mr. Bush responded.

“We all got a big laugh out of that,” said Patrick Kennedy.

After the meeting broke up, Mr. Bush walked Ted and Patrick Kennedy out through the columns at the front entrance to the White House and saw the senator off in a blue van. Then Mr. Bush walked back to the Oval Office with Patrick Kennedy and they said their goodbyes.

jmulligan@belo-dc.com