 On 6 October 1955 , Diệm announced the referendum would be held on 23 October . The election was open to men and women aged 18 or over , and the government arranged to have a polling station set up for every 1 @,@ 000 registered voters . The poll was contested by Bảo Đại , who had spent much of his time in France and advocated a monarchy , and Diệm , who ran on a republican platform . According to historian Jessica Chapman , it was a choice between " the country 's obsolete emperor and its far @-@ from @-@ popular prime minister , Ngo Dinh Diem " . In announcing the referendum , Diệm portrayed his decision as being motivated by a love of democracy and popular discontent with the rule of Bảo Đại . The prime minister cited a plethora of petitions from various social , religious , and political groups calling on him to stage a plebiscite to remove Bảo Đại , claiming he was motivated by these " legitimate and democratic " sentiments . Lansdale cautioned Diệm against electoral fraud , confident that Diệm would win a free election : " While I 'm away I don 't want to suddenly read that you have won by 99 @.@ 99 % . I would know that it 's rigged then . " U.S. officials thought that a fair election would have seen Diệm poll between 60 % and 70 % of the vote . 
