張勉
In the 1950s, the governing Liberal Party was led by President Syngman Rhee. In April 1952, opposition lawmakers and some Liberal Party lawmakers attempted a constitutional amendment but were branded enemies of the state by Syngman Rhee When the assembly voted to have martial law lifted in Busan, Rhee had half of them arrested. After a staged assassination attempt on Rhee, police began to investigate alleged links to the opposition. Police claimed that Chang Myon was working with assassins paid by North Korea to depose Rhee. Under this type of pressure, the assembly voted 160 to zero for Rhee's constitutional amendments. By the late 1950s Chang Myon emerged as the major alternative to Rhee, and in 1960, when Rhee was overthrown by the April 19th Movement and a popular revolution, Chang Myon was elected the Prime Minister of the Second Republic of Korea and "de facto" chief executive.