Robert John Day (born 5 July 1952) is an Australian former politician and businessman who was a Senator for South Australia from 1 July 2014 to 1 November 2016. He is a former federal chairman of the Family First Party. Before entering politics, he worked in the housing industry, owning several businesses, and at one stage serving as president of the Housing Industry Association. Day was the Liberal Party's candidate for the federal seat of Makin at the 2007 election, but resigned from the party after failing to gain preselection for the 2008 Mayo by-election. He subsequently joined the Family First Party and was their candidate for the by-election, later becoming their lead Senate candidate in South Australia at the 2010 election and 2013 election. On his fourth attempt to enter federal parliament in 2013, Day was elected to the Senate from a 3.8 per cent primary vote for Family First, to a term beginning on 1 July 2014. Despite a decline in the party's vote to 2.9 per cent, he was re-elected at the 2016 double dissolution election. Elected to the 12th and final South Australian Senate spot, Day's term was due to expire on 30 June 2019. Following the liquidation of Home Australia Group, Day announced his intention to resign from the Senate. However, he stated that a potential new investor had expressed interest in the business, that there was too much important work for the Family First Senate seat to be vacant for even one day and that therefore he would not resign before the year's end. However, Day resigned on 1 November 2016 after stating that the investor had backed out. On 5 April 2017 the High Court held that Day's re-election to the Senate in July 2016 was invalid, since he'd had an "indirect pecuniary interest" in an agreement with the Commonwealth since at least February 2016. As a result, he had not been eligible to sit as a senator from at least February 2016 onward by reason of section 44(v) of the Constitution. Early life Day was born in Manchester, UK, on 5 July 1952. He came to Australia as a child in 1963. Day attended Gilles Plains High School and the University of South Australia. Career Day's career started in the South Australian public service at the Materials and Research Laboratories of the former Highways Department, now part of the Department of Planning,