Holt increased Australian commitment to the growing War in Vietnam, which met with some public opposition. His government oversaw conversion to decimal currency. Holt faced Britain's withdrawal from Asia by visiting and hosting many Asian leaders and by expanding ties to the United States, hosting the first visit to Australia by an American president, his friend Lyndon B. Johnson. Holt's government introduced the Migration Act 1966, which effectively dismantled the White Australia Policy and increased access to non-European migrants, including refugees fleeing the Vietnam War. Holt also called the 1967 Referendum which removed the discriminatory clause in the Australian Constitution which excluded Aboriginal Australians from being counted in the census – the referendum was one of the few to be overwhelmingly endorsed by the Australian electorate (over 90% voted 'yes'). By the end of 1967, the Liberals' initially popular support for the war in Vietnam was causing increasing public protest.