A fresh leadership scrap inside Australia’s ruling Labour Party prompted opposition Liberal leader Tony Abbott to demand a parliamentary election scheduled for September 14 be brought forward to August 3.

“What the Australian people want is their chance to choose the government and to choose the prime minister,” he said. “The only way they’ll get that is if there’s an election.” The demand came as serial leadership contender Kevin Rudd marshalled support for a fresh challenge to Prime Minister Julia Gillard, who deposed him three years ago.

Supporters maintain that Rudd’s popularity could save Labour from a landslide loss in September.

Gillard is refusing to stand aside, a tactic that could force Rudd to break a promise he made after an earlier failed challenge, that he would never again mount a formal bid for her job.

If Rudd decides to run, the issue would be resolved in a party-room vote on Thursday. At least one third of the 102 Labour members of parliament would have to sign a petition to bring on a ballot among members.

In March, when supporters brought on a vote, Rudd shocked them by refusing to stand.

The timing of parliamentary elections, and therefore whether to bring them forward, is decided by the prime minister of the day.

Foreign Minister Bob Carr, who earlier in the day refused to endorse Gillard’s leadership, said she would not be attending the September 5-6 G20 Leaders Summit in Russia in September because it comes just two weeks before the scheduled election.

“I would think there’d be a precedent for countries being caught in domestic matters and not being able to be represented by the head of government,” Carr said.

“I don’t think that represents anything that can’t be managed.” The opposition said it would be “grossly negligent” for the Prime Minister not to attend, given that Russia is to hand over the chair of the G20 to Australia at the St Petersburg meeting.