Advertisement There was a time in Australian politics when rolling the leader of a political party mid-term, like some Liberals wish to do to Opposition Leader Michael OâBrien, was the ultimate act of treachery. That treachery intensified when the public felt like they had some role in installing the leader to their position, and therefore had a buy-in. For so long, it was an unwritten rule of politics that such an act of bastardry would come with a transaction cost. In economics, a transaction cost is the expenses incurred when buying or selling goods like an agentâs commission or brokerâs fee. In politics it usually comes in the form of a dip in the polls or encounters with angry constituents.