After thinking about it for a moment, Carter smiled.
"I wish I had sent one more helicopter to get the hostages, and we would've rescued them, and I would've been reelected," Carter said.
Carter lost reelection in 1980 to California Gov. Ronald Reagan. Analysts and historians generally chalk up Carter's loss to a lackluster economy and the Iranian hostage crisis.
Fifty-two American hostages who were taken from the embassy in Iran and held for months during Carter's presidency. The crisis culminated when eight US servicemen were killed during a failed rescue operation in April 1980, months before the election.
See photos of the former U.S. President below:
Jimmy Carter through the years
Jimmy Carter: I have one big regret from my time as president
Jimmy(James Earl) Carter as Ensign, USN, circa World War II. (Photo by PhotoQuest/Getty Images)
American politician and US Presidential candidate Jimmy Carter holds a handful of peanuts (referencing his career as a peanut farmer) during a campaign event, Boston, Massachusetts, 1976. (Photo by Mikki Ansin/Getty Images)
American politician and US Presidential candidate Jimmy Carter (center) smiles after his victory in the Pennsylvania Primary election, Philadelphia, Pennsylvania, April 27, 1976. Among those on stage with him are politicians Samuel L Evans (left) and Senator Birch Bayh (second left). (Photo by Mikki Ansin/Getty Images)
U.S. president Jimmy Carter smiling at a podium in front of an American flag, 1970s. (Photo by Hulton Archive/Getty Images)
1976: A campaign button supporting the Democratic politician Jimmy Carter for President. (Photo by MPI/Getty Images)
Jimmy Carter on his peanut farm, Plains, Georgia, 1976. (Photo by PhotoQuest/Getty Images)
Jimmy Carter (left) and Sen. Walter Mondale at the 1976 Democratic National Convention at Madison Square Garden. (Photo by James Garrett/NY Daily News Archive via Getty Images)
Photograph of President Jimmy Carter and First Lady Rosalynn Carter dancing at a White House Congressional Ball. Photographed by Marion S. Trikosko. Dated 1977. (Photo by: Universal History Archive/UIG via Getty Images)
Jimmy Carter of Plains, GA, was the 39th President of the United States and a big fan of NASCAR racing. In 1978, Carter invited a number of NASCAR Cup stars to the White House for a big dinner and entertainment provided by country star Willie Nelson. Nelson was there and so were First Lady Rosalynn Carter and the President's brother Billy Carter, but President Carter was nowhere to be found. The President had gone to Camp David to meet with the leaders of Israel and Egypt, Menachem Begin and Anwar Sadat, in what ultimately would lead to a huge Middle East peace agreement known later as the Camp David Accords. (Photo by ISC Images & Archives via Getty Images)
Jean-Paul II In Washington, United States On October 06, 1979)-John-Paul II, Jimmy Carter and Rosalyn at the White House. (Photo by Pool JEAN-PAUL II AUX USA/Gamma-Rapho via Getty Images)
Photograph of President Jimmy Carter announcing new sanctions against Iran following the taking American hostages. Photographed by Marion S. Trikosko. Dated 1980. (Photo by: Universal History Archive/UIG via Getty Images)
Gerald Ford and Jimmy Carter during Humanitarian Awards Dinner - November 23, 1987 at Waldorf Astoria Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
Gillian Sorenson and Jimmy Carter during Benefit Dinner Dance for the Homeless - November 18, 1988 at Plaza Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
Musician Willie Nelson and former President Jimmy Carter at the taping of 'CMT Homecoming: Jimmy Carter in Plains,' which will premiere on CMT in December 2004. (Photo by Rick Diamond/WireImage)
ATLANTA - APRIL 22: Former President Jimmy Carter watches the game between the Philiadelphia Phillies and the Atlanta Braves at Turner Field on April 22, 2010 in Atlanta, Georgia. (Photo by Kevin C. Cox/Getty Images)
CAIRO, EGYPT - MAY 24: Former U.S. President Jimmy Carter addresses the media on the second day of Egypt's presidential election on May 24, 2012 in Cairo, Egypt. Carter Center election monitors observed the presidential election, the first of the post-Mubarak era. If no candidate wins an outright majority of the vote, the election would go to a second round June 16-17. (Photo by John Moore/Getty Images)
Former US President Jimmy Carter signs his new Book 'A Full Life: Reflections at Ninety' at Barnes & Noble on 5th avenue in New York on July 7, 2015. Photo by KENA BETANCUR/AFP/Getty Images
PASADENA, CA - JULY 30: President Jimmy Carter photographed at Vroman's Bookstore on July 30, 2015 in Pasadena, California. (Photo by Paul Redmond / Getty Images)
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Carter emphasized Thursday that his work with the Carter Center — a sprawling nonprofit that does everything from fight disease to help peace negotiations abroad — has been more personally satisfying to him than his four years as president, but he admitted that he would've liked to serve another term.
"That may have interfered with the Carter Center. If I had to choose between four more years and the Carter Center, I would've chosen the Carter Center. But it could've been both," Carter said, smiling.
In 2014, Carter said that he could've "wiped Iran off the map," but instead opted for a helicopter rescue mission that failed.
"I think I would have been reelected easily if I had been able to rescue our hostages from the Iranians," Carter told MSNBC last year. "And everybody asks me what [I] would do more. I would say I would send one more helicopter because if I had one more helicopter, we could have brought out not only the 52 hostages, but also brought out the rescue team. And when that failed, then I think that was the main factor that brought about my failure to be reelected. So that's one thing I would change."
Though Thursday's press conference focused primarily on Carter's health and plans for treatment, the former president took numerous questions from journalists and reflected on his life and personal accomplishments.
"I've had a wonderful life. I have thousands of friends. I've had an exciting, adventurous, and gratifying existence," Carter said.
Carter jokes he'd like "the last guinea worm to die before I do" his Center fights worm-caused disease.