New South Wales Labor suffers election bus mishap, as campaigning goes west four days out from vote

The electric bus was replaced by a conventional diesel bus for the remainder of the day. (AAP: Bianca De Marchi )

With dozens of journalists watching their every move, the last thing any politician wants on the election campaign trial is car trouble. 

But NSW Labor's electric bus hit a speed bump in western Sydney on Tuesday, forcing everyone on board to swap to a petrol bus.