Acting Opposition Leader Julie Bishop has dodged questions about Brendan Nelson's tenuous leadership after another dip in his approval rating.
Dr Nelson, who is in the United States to discuss economics, climate change and security with political leaders, has suffered another drubbing in the latest Newspoll published in The Australian newspaper.
Despite the government facing pressure over deteriorating economic conditions and the high cost of living, Labor remains in a commanding position with a two-party preferred vote of 57 per cent, against the coalition on 43 per cent.
On a two-party basis, their support levels were unchanged from the last Newspoll.
However, the Nationals' primary vote inched up from four to five per cent.
Prime Minister Kevin Rudd's approval rating stayed static, but Dr Nelson, who has struggled in recent weeks to come up with a coherent climate change policy, saw his satisfaction rating go down and dissatisfaction with his performance go up.
Thirty-one per cent were satisfied with Dr Nelson, down from 33 per cent, while the dissatisfaction rating climbed from 42 per cent to 48 per cent.
The poor polling will add to pressure on Dr Nelson's leadership.
Former treasurer Peter Costello is preferred by more voters but he is unwilling to say whether he wants the Liberal leadership until he releases his memoirs in mid September.
Ms Bishop told Sky News that opinion polls were one thing, but Labor had experienced a drop in support at every election since it won power federally on November 24.
"(At every election) there's been a massive swing against Labor," she said.
After a surprise swing to the Country-Liberal Party in the Northern Territory election on Saturday, Labor clawed back a lead in the seat of Fannie Bay to retain government with a one-seat majority.
"I think that reflects the disillusionment that people have about Labor governments across the country," Ms Bishop said.
Federal Labor experienced an 8.5 per cent swing against it in the Victorian seat of Gippsland, formerly held by Nationals minister Peter McGauran.
The next major test will be on September 6, when West Australians go to the polls and there are by-elections in the seats of Mayo - vacated by former foreign minister Alexander Downer - and Lyne, vacated by former deputy prime minister Mark Vaile.