A promise to return Australia's budget to surplus within 12 months and cash handouts for voters failed to improve the ruling Labor party's ailing popularity, according to the latest polls.

Prime Minister Julia Gillard had hoped Tuesday's budget would boost Labor's standing following a series of scandals which have rocked her fragile minority government, but both she and her party continued to slip in the opinion polls.

A Nielsen survey of 1,200 voters published in the Sydney Morning Herald put centre-left Labor's vote at 42 percent to the conservatives' 58 percent, a one-point drop from the previous poll conducted in late February.

Were an election held today, Liberal/National leader Tony Abbott would storm to power, with voters preferring him as prime minister by 50 percent to Gillard's 42 percent, compared with 48 to 45 percent in February.

Gillard also continued to lag her predecessor Kevin Rudd as preferred Labor leader 30 percent to his 62 percent.

Rudd was deposed as leader ahead of the 2010 election in a shock party-room ouster and lost a challenge to Gillard's leadership earlier this year, but he remains popular with voters.

Some 50 percent of those polled this week said Labor should change leaders, while 45 percent called for the party to stay with Gillard, who is struggling to sell unpopular policies and battling dual scandals.

She ordered Labor MP Craig Thomson to quit the party in April over damaging allegations that he used a former employer's credit card to pay for prostitutes before he came to parliament.

Parliamentary Speaker Peter Slipper -- a Gillard appointment -- was also sidelined after a staffer accused him of sexual harassment and of misusing government travel benefits.

The controversies overshadowed Labor's promise to return the budget to surplus this year by cutting $33.6 (US$33.7) billion in government spending but softening the blow to low and middle-income earners with a raft of handouts.

Elections are not due until 2013 but Gillard is under constant pressure from the Abbott opposition to call an early poll as the scandals test her shaky one-seat majority.