Bucking a tradition dating back to Washington, FDR refused to step down after serving two terms, announcing that he would run for an unprecedented third consecutive term as chief executive. His political opponents, including some within his own party, were understandably up in arms. Following Roosevelt's renomination in the summer of 1940, a coalition of irate Republicans and disgruntled Democrats rallied under the "No Third Term" banner.
One anti-FDR faction, calling itself the Constitutionalists, argued that while the president was not explicitly barred from serving more than two terms, an extended tenure would violate the balance of powers outlined in the nation's foundational document. The electorate was unpersuaded, however, returning Roosevelt to office in 1940 and again, for a fourth term, in 1944.
The naysayers did eventually have their day, albeit after FDR's death, with the passage of the 22nd Amendment (1951), which imposed the presidential two-term limit.