WASHINGTON — Barbara Bush, the seriously ill wife and mother of presidents who has long been among the most popular members of her famous family, has decided to stop seeking medical treatment to prolong her life, a spokesman said on Sunday.

Mrs. Bush, who is 92 and frail, has been in and out of the hospital but has now forsworn further interventions and “will instead focus on comfort care,” according to a statement issued by her husband’s office in Houston.

“It will not surprise those who know her that Barbara Bush has been a rock in the face of her failing health, worrying not for herself — thanks to her abiding faith — but for others,” the statement said. “She is surrounded by a family she adores, and appreciates the many kind messages and especially the prayers she is receiving.”

Mrs. Bush was resting at the family home in Houston. Her husband, former President George Bush, was with her, along with her children Neil, Marvin and Dorothy. Her two eldest sons, former President George W. Bush and former Gov. Jeb Bush of Florida, have both been to visit in recent days and were calling frequently on Sunday, according to a person close to the family.