Ian Macfarlane's failed attempt to switch from the Liberal Party to the Nationals highlights problems in Queensland's merger of the two main anti-Labor parties and suggests tensions within the federal Coalition. With a leadership change looming for the Nationals, Peter Clarke talks to Brian Costar, emeritus professor of politics at the Swinburne Institute for Social Research, about Barnaby Joyce, Malcolm Turnbull and the balancing act that keeps the Coalition afloat. Interview originally appeared on the Inside Story website, 18 December 2015.