This coalition appeared to work until February 1963, when the larger BDG forced the UDSG members to choose between a merger of the parties or resignation. The UDSG cabinet ministers resigned, and M'Ba called an election for February 1964 and a reduced number of National Assembly deputies (from 67 to 47). The UDSG failed to muster a list of candidates able to meet the requirements of the electoral decrees. When the BDG appeared likely to win the election by default, the Gabonese military toppled M'Ba in a bloodless coup on February 18, 1964. French troops re-established his government the next day. Elections were held in April with many opposition participants. BDG-supported candidates won 31 seats and the opposition 16. Late in 1966, the constitution was revised to provide for automatic succession of the vice president should the president die in office. In March 1967, Leon M'Ba and Omar Bongo (then Albert Bongo) were elected president and vice president. M'Ba died later that year, and Omar Bongo became president.