Entering parliament in 1997 at the age of 24, he was the youngest member of the House of Assembly at the time. He was
Speaker of the South Australian House of Assembly for the
Rann Labor government from 2006 to 2010. He also served as Deputy Speaker and Chairman of Committees. He is aligned with Labor's right faction. A consequence of the major
2016 electoral redistribution was that two thirds of the voters in Snelling's electorate of
Playford will be moved to
Florey. On 15 March 2017 he won
Labor preselection to be the candidate for Florey at the
2018 election. The incumbent member for Florey,
Frances Bedford, had also nominated for pre-selection. On 28 March 2017, Bedford resigned from the party after they endorsed Snelling for the seat. A ReachTEL poll conducted on 2 March 2017 of 606 voters in post-redistribution Florey indicated a 33.4 percent primary vote for Bedford running as an independent which would likely see Snelling defeated after preferences. Snelling withdrew from the pre-selection on 17 September 2017. Following the parliamentary resignation of
Kevin Foley, Snelling was sworn in as the
Treasurer of South Australia on 8 February 2011. Once the ALP had retained power (though dependent on an independent parliamentarian's support) at the
2014 election, Snelling was appointed as the Minister for Health, Minister for Mental Health and Substance Abuse, Minister for the Arts and Minister for Health Industries in the
Weatherill Labor cabinet. He resigned from Cabinet on 17 September 2017, and announced that he would not be contesting the 2018 election, for which he had been preselected to the seat of
Florey. He also served as
Leader of Government Business in the House of Assembly until 2017.
Outside parliament On 28 July 2021, alongside former minister
Tom Kenyon, Snelling founded the
Family First Party, saying that "we are very concerned about religious freedom and attempts to restrict that freedom". == Personal life ==