FILE — From left, former President George H.W. Bush, President-elect Barack Obama, President George W. Bush, former President Bill Clinton and former President Jimmy Carter meet in the Oval Office at the White House in Washington, on Jan. 7, 2009. (AP Photo/J. Scott Applewhite, File)

FILE - President Jimmy Carter is seen with former President Gerald Ford aboard Air Force 1 between Cairo and Spain on Oct. 10, 1981. (AP Photo/Dirck Halstead, File)

FILE - Former President Jimmy Carter, left, speaks during a Rose Garden ceremony to unveil the report by the National Commission on Federal Election, July 31, 2001, at the White House in Washington as President Bush looks on at right. (AP Photo/Ron Edmonds, File)

FILE - From left, President Donald Trump, first lady Melania Trump, former President Barack Obama, former first lady Michelle Obama, former President Bill Clinton, former Secretary of State Hillary Clinton, former President Jimmy Carter and former first lady Rosalynn Carter participate in the State Funeral for former President George H.W. Bush at the National Cathedral on Dec. 5, 2018, in Washington. (AP Photo/Alex Brandon, Pool, File)

FILE - Former U.S. President Jimmy Carter, right, shakes hands with Nicaraguan President Daniel Ortega during elections in Managua, Feb. 24, 1990. In background in between Carter and Ortega is former first lady Rosalyn Carter. (AP Photo, File)

FILE - This photo provided by the North Korean government shows former U.S. President Jimmy Carter, left, and then North Korean President Kim Il Sung looking at the West Sea Barrage in Nampo, North Korea, on June 17, 1994. (Korean Central News Agency/Korea News Service via AP, File)

FILE - Former presidents Gerald Ford, Richard Nixon and Jimmy Carter, and former first lady Rosalynn Carter stand atop the ramp to an Air Force jet on Oct. 8, 1981, at Andrews Air Force Base, Md., just before their departure to attend the funeral in Cairo for slain Egyptian President Anwar Sadat. (AP Photo/John Duricka, File)

FILE - U.S. President Bill Clinton, flanked by former Presidents George Bush, left, and Jimmy Carter, walks through the Colonnades of the White House, Washington, on Sept. 13, 1993. (AP Photo/Wilfredo Lee, File)

FILE - Former Presidents Gerald Ford and Jimmy Carter share a light moment as they take a break from their Symposium on New Weapons Technologies and Soviet-American Relations at the University of Michigan to talk with reporters on Nov. 14, 1984, in Ann Arbor, Mich. (AP Photo/Rob Kozloff, File)

FILE - Former President George W. Bush, left, sits with President Barack Obama, right, and first lady Michelle Obama, center, at the dedication ceremony for the Smithsonian Museum of African American History and Culture on the National Mall in Washington on Sept. 24, 2016. (AP Photo/Pablo Martinez Monsivais, File)

FILE - President George Bush, former President Ronald Reagan, former President Jimmy Carter, former President Gerald Ford and former President Richard Nixon attend the dedication ceremony for the Ronald Reagan Presidential Library in Simi Valley, Calif, on Nov. 5, 1991. (AP Photo/Marcy Nighswander, File)