Williams was a member of the Liberal Party when he resigned in 1997 to run against
Dale Baker as an independent in MacKillop, based on
Millicent. Williams took advantage of a public backlash against Baker, who was accused of impropriety over a forestry land deal. At the 1997 election, Williams halved Baker's primary vote and was elected on
Labor preferences. Williams was one of three conservative crossbenchers whose support kept the Liberal government of
John Olsen in office after the Liberals lost their previous overwhelming majority. He rejoined the Liberal Party in December 1999, giving the Liberals a majority of one seat until
Peter Lewis was expelled from the party in July 2000. Williams was handily re-elected in MacKillop in 2002, 2006, 2010, and 2014. Williams was elected unopposed as Deputy Leader of the Liberal Party in South Australia on 6 April 2010. On 19 October 2012,
Martin Hamilton-Smith announced he would be challenging
Isobel Redmond for the parliamentary leadership of the South Australian Liberal Party, with
Steven Marshall challenging Williams for the deputy leadership. A partyroom ballot occurred on 23 October 2012, Redmond retained the leadership by one vote, however Marshall was elected to the deputy leadership after Williams withdrew at the last minute. Williams did not re-contest his seat at the
2018 election. == Political views ==