Atlanta, Georgia - Former President Jimmy Carter made a rare public appearance on Tuesday to join two of his successors and all five living first ladies at the memorial service for his wife Rosalynn.

A frail-looking Carter (99), who has been in hospice care for several months, arrived in a wheelchair at the Glenn Memorial Church in Atlanta for the ceremony.

Rosalynn Carter was a humanitarian and mental health advocate who died on November 19 aged 96. Rosalynn Carter had been suffering from dementia and died just two days after joining her husband in hospice care at their home in Plains, Georgia.

Celebrated as an active first lady who championed then little-discussed issues of mental health, Rosalynn Carter's reputation for humanitarianism grew along with her husband's once they left the White House.

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When she died, Jimmy Carter said in a statement that she'd been "my equal partner in everything I ever accomplished."

Rosalynn Carter's farewell began Monday when past and present agents from the US Secret Service, which guards presidential families, escorted her coffin to the Jimmy Carter Presidential Library and Museum in Atlanta. The public was invited to pay last respects.

The more private funeral on Wednesday in Plains will inevitably shift attention to the health of Jimmy Carter, who is the oldest living US ex-president in US history.

Sitting next to Carter in the church were current US President Joe Biden and First Lady Jill Biden, who watched as Rosalynn Carter's flower-covered coffin was carried in.

Alongside them were former President Bill Clinton, former Secretary of State Hillary Clinton, as well as former first ladies Melania Trump, Michelle Obama, and Laura Bush.

Presidential funeral services are typically attended by all living presidents, providing a moment of unity across parties and generations.

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With Biden and Donald Trump likely to face each other in a 2024 rematch of their bitter 2020 election battle, however, even the solemn occasion of a Carter funeral would be scrutinized for signs of tension.

The turnout of US political luminaries showed the high regard in which Rosalynn Carter was held by her country.