Wentworth By-Election: Prospects And Polls

WENTWORTH (Lib vs ALP, 17.8%)
Cause of vacancy: Resignation of Malcolm Turnbull

A by-election for Wentworth has been set down for Saturday 20 October following the resignation from parliament of the former Prime Minister, Malcolm Turnbull.  This post will give an assessment of how this by-election stands in history and will also comment critically on polling. As I start it on 14 Sep I won't be brave enough to predict the winner yet, but I may do so later [edit: as of the final week I am not liking the Liberals' chances of holding off Phelps at all].  This post will be updated with new polls and changed assessments through to polling day.

By-elections often produce big swings against governments, but surely 17.8% is safe?  After all, there has only been one larger swing in federal by-election history (20.1% in Wakefield, 1938).  In fact there are at least two reasons not to take the seat's safety for granted.  These are the historic circumstances of the by-election and the prospect of losing the seat to an independent.  While I've seen some spinning suggesting that a double-digit swing should be viewed as a shocker for the Liberal Party even if they don't lose the seat, I think the circumstances are so unusual that they'd take a win by any margin now.