The polls are expected to be fought over policies on economic management, climate and border protection.
Gillard took over from Rudd on June 24 as the ruling Labor party faced electoral defeat over a series of unpopular decisions by Rudd's government, and has been frantically clearing the decks of the thorny issues.
The former deputy to Rudd recently announced a policy on how to handle an influx of boat people and also watered down a disputed mining tax that some say ultimately sank Rudd.
She has enjoyed a polls jump to put Labor narrowly ahead of the Conservative opposition in opinion polls - but has also faced a backlash over plans to outsource the processing of asylum seekers to Pacific nations and about the manner in which she came to power.
Gillard, who said when she came to power that Rudd's government had lost its way, said she had begun getting it back on track by announcing plans for the regional asylum seeker processing centre and resolving a battle with miners over the now axed super tax.
"Through doing those things I've demonstrated to the Australian people the kind of way which I will lead the nation," she said on Saturday.
"This election I believe presents Australians with a very clear choice - the choice is about whether we move Australia forward or go back," Gillard said, adding that "moving forward means moving forward with budget surpluses and a stronger economy".
But the Conservatives, led by Tony Abbott, need to win only nine seats to form the government with four independents, or 13 seats to take office outright, and Abbott wasted no time on Saturday, saying "we are ready to govern" in a speech focused on jobs.
"Trust will only be restored by demonstrating, over time, that the coalition again has the steady hands in which people's job security and pay and conditions can once more safely rest," he said.
Dennis Shanahan, the political editor of The Australian newspaper, told Al Jazeera that there were two main reasons for Gillard calling elections so soon after taking over from Rudd.
"The first reason is she needed to legitimise her prime ministership," he said. "She's been criticised a lot for the manner of the removal of Kevin Rudd as prime minister."
"[Gillard] has had one of the shortest honeymoons in political history. The polls are beginning to turn, and her strategists have said to her, 'go now, go soon before it gets worse'"
Dennis Shanahan, political editor of
"Secondly, she has had one of the shortest honeymoons in political history. The polls are beginning to turn, and her strategists have said to her, 'go now, go soon before it gets worse'."
Despite Labor steering the economy through the global financial crisis and avoiding recession, and the government's pledge to return a budget surplus by 2013, opinion polls show voters view the opposition as better economic managers.
Abbott has led an attack on the government over its A$52bn ($45bn) economic stimulus spending that helped Australia pull through the global economic recession with only a single quarter of mild economic contraction in late 2008.
Abbott told a conservative party meeting in Queensland, a key state to the outcome of the next election, that the government had wasted money and the leadership change from Rudd to Gillard was a "seamless transition from incompetence to incompetence."
"The people of Queensland won't be conned by a prime minister who is now running to the polls before she has established her credentials to lead our nation," Abbott said.
"Tony Abbott has already demonstrated that he's prepared to go bare-knuckles. He's saying the previous government under Kevin Rudd had failed, that's why Julia Gillard 'executed' him," Shanahan told Al Jazeera.
"He's using all of this tough language and he is saying that the government doesn't deserve a second chance.
|Border protection, economic and climate policies, are set to be key battle grounds [AFP]
"He's going in very hard, particularly on economic failure and border protection with asylum seekers."
Shanahan explained that cost of living and rising interest rates were a real consideration for this campaign. And on the asylum-seeker issue, he said Rudd "had allowed the issued of immigration, growing population and the arrival of illegal boats with people smugglers, to become all combined into one issue".
Gillard was trying to separate out the issues, he said, "but one of the big fears the Labor party has is the continuing arrival of illegal boats during the campaign".
Shanahan said the election was "too close to call" and both leaders have said "it's going to be tough, hard and close".
While voters will be given policy choices, they will also face two contrasting personalities in Abbott and Gillard.
Abbott is a pugnacious and socially conservative Catholic, who once trained for the priesthood, and is opposed to same sex marriages and abortions.
Gillard is an atheist, is unmarried but has a long-time partner, and is childless.