As Trump says "there are methods" for serving a third term, here's what to know about the 12th and 22nd Amendments

President Trump has periodically floated the idea of serving a third term in office since his first reelection campaign and seemed to double down on it Sunday during an interview with NBC News, suggesting "there are methods" to do it despite term limits set by the 12th and 22nd Amendments in the U.S. Constitution.

To date, Franklin D. Roosevelt is the only president in the history of the United States to serve more than two terms, ultimately sitting in office from 1933 to 1945. His third term was controversial, said Noah Rosenblum, a legal historian and constitutional law professor at New York University, noting that FDR's tenure broke from a precedent set by George Washington and drew accusations of dictatorial ambitions as well as a disrespect for democracy.

"There are very few norms as deeply embedded in American democratic culture as the idea that the president serves two terms," Rosenblum told CBS News. "And clever word games to how to get around that are really nothing but attempts to undermine the clear text, spirit and intention of the Constitution and this historical process that ungirds it."