A GOVERNMENT MP clinging to the most marginal Labor seat in Queensland says he will quit politics and force a byelection should Julia Gillard be dumped as prime minister.

In a threat which has the potential to bring down the government, Graham Perrett told the Herald Labor was wrong to remove a prime minister last year and he would not be a party to such an act again.

Labor MP Graham Perrett ... don't dump a second PM. Credit:Alex Ellinghausen

Despite holding his Brisbane seat of Moreton by 1.1 per cent, meaning he would be wiped out if the polls did not improve, Mr Perrett said dumping Kevin Rudd had been a breach of faith with his voters.

''I will not be breaking faith with the people of Moreton. I did it in 2010 and I've been constantly reminded by my voters that I did that,'' he said.