ATLANTA — Former first lady Rosalynn Carter, the closest adviser to Jimmy Carter during his one term as U.S. president and their four decades thereafter as global humanitarians, has died at the age of 96.

The Carter Center said she died Sunday after living with dementia and suffering many months of declining health. The statement announcing her death said she “died peacefully, with family by her side” at 2:10 p.m. at her rural Georgia home of Plains.

“Rosalynn was my equal partner in everything I ever accomplished,” Carter said in the statement. “She gave me wise guidance and encouragement when I needed it. As long as Rosalynn was in the world, I always knew somebody loved and supported me.”

President Biden called the Carters “an incredible family because they brought so much  grace to the office” and also spoke of the couple’s “great integrity.”

“Imagine they were together for (77) years?” Biden said. “God bless them.”

Jill Biden, who made an appearance earlier Sunday with the president at Naval Air Station in Norfolk, Virginia, said of Rosalynn Carter that she “was well-known for her efforts on mental health and caregiving and women’s rights. So I hope that during the holidays, you’ll … include the Carter family in your prayers.”

The Carters were married for more than 77 years, forging what they both described as a “full partnership.” Unlike many previous first ladies, Rosalynn sat in on Cabinet meetings, spoke out on controversial issues and represented her husband on foreign trips. Aides to President Carter sometimes referred to her — privately — as “co-president.”

“Rosalynn is my best friend … the perfect extension of me, probably the most influential person in my life,” Jimmy Carter told aides during their White House years, which spanned from 1977-1981.

The former president, now 99, remains at the couple’s home in Plains after entering hospice care himself in February.

Fiercely loyal and compassionate as well as politically astute, Rosalynn Carter prided herself on being an activist first lady, and no one doubted her behind-the-scenes influence. When her role in a highly publicized Cabinet shakeup became known, she was forced to declare publicly, “I am not running the government.”

Many presidential aides insisted that her political instincts were better than her husband’s — they often enlisted her support for a project before they discussed it with the president. Her iron will, contrasted with her outwardly shy demeanor and a soft Southern accent, inspired Washington reporters to call her “the Steel Magnolia.”

Both Carters said in their later years that Rosalynn had always been the more political of the two.

As honorary chairwoman of the President’s Commission on Mental Health, she once testified before a Senate subcommittee, becoming the first first lady since Eleanor Roosevelt to address a congressional panel. She was back in Washington in 2007 to push Congress for improved mental health coverage, saying, “We’ve been working on this for so long, it finally seems to be in reach.”

She said she developed her interest in mental health during her husband’s campaigns for Georgia governor.

“I used to come home and say to Jimmy, ‘Why are people telling me their problems?’ And he said, ‘Because you may be the only person they’ll ever see who may be close to someone who can help them,’” she explained.

Jimmy Carter is the longest-lived U.S. president. Rosalynn Carter was the second longest-lived of the nation’s first ladies, trailing only Bess Truman, who died at age 97.

Eleanor Rosalynn Smith was born in Plains on Aug. 18, 1927, the eldest of four children. Her father died when she was young, so she took on much of the responsibility of caring for her siblings when her mother went to work part time.

She also contributed to the family income by working after school in a beauty parlor. “We were very poor and worked hard,” she once said, but she kept up her studies, graduating from high school as class valedictorian.

She soon fell in love with the brother of one of her best friends. Jimmy and Rosalynn had known each other all their lives — it was Jimmy’s mother, nurse Lillian Carter, who delivered baby Rosalynn — but he left for the Naval Academy in Annapolis, Maryland, when she was still in high school.

Jimmy and Rosalynn had known each other all their lives — it was Jimmy’s mother, nurse Lillian Carter, who delivered baby Rosalynn — but he left for the Naval Academy in Annapolis, Maryland, when she was still in high school.

After a blind date, Jimmy told his mother: “That’s the girl I want to marry.” They wed in 1946, shortly after his graduation from Annapolis and Rosalynn’s graduation from Georgia Southwestern College.

Their sons were born where Jimmy Carter was stationed: John William (Jack) in Portsmouth, Virginia, in 1947; James Earl III (Chip) in Honolulu in 1950; and Donnel Jeffery (Jeff) in New London, Connecticut, in 1952. Amy was born in Plains in 1967. By then, Carter was a state senator.

President Jimmy Carter, right, and his wife, first lady Rosalynn Carter, lead their guests in dancing at the annual Congressional Christmas Ball, Dec. 13, 1978, at the White House in Washington.
Former President Jimmy Carter, right, holds hands with his wife, former first lady Rosalynn Carter, as they work with other volunteers on site, Aug. 27, 2018, in Mishawaka, Ind. (Robert Franklin/South Bend Tribune via AP, File)