The by-election is occasioned by the loss of seat by a member through death, resignation or ejection from his/her party. By-elections are often tests of government popularity; in the case of Senate by-elections, they're a double-edged opportunity to change the overall balance of political power. The electorate generally hates them and usually punish a resigner; in recent times, they have increasingly opted to return an independent as a protest, eg Bob Katter left the National party because he felt the Coalition was not serving his constituents: he was returned as an independent with a massive majority in one of the country's biggest seats. He serves as a warning to politicians of all persuasions.