Prime Minister Tony Abbott is nearing the end of his first full year in office hobbled by missteps and a souring economy that have plunged his approval ratings to historic lows, increasing speculation he may not survive to a second term.

Faced with a collapse in commodities prices and an unruly upper house Senate that has held his first budget hostage since May, voters have abandoned his conservative government more quickly than any other in three decades.

The drum beat of bad news, most recently the thrashing handed to Abbott's Liberal-National coalition in state elections in Victoria on Saturday, has sparked calls for Treasurer Joe Hockey and Defense Minister David Johnston to be thrown out.