After the election was announced, Abbott promised to "get the budget back under control," and listed scrapping the unpopular carbon tax among his top priorities if elected.
The election promises to be an extraordinary contest for Australian politics. Labor leads Australia's first minority government since World War II, and polls suggest the opposition faces an easier task picking up seats than Labor does.
Labor holds 71 seats in the 150-seat House of Representatives where parties form governments. The opposition holds 72 seats, with the remainder held by independent lawmakers or sole legislators from minor parties.
A recent poll has shown that secrets spiller Julian Assange and his WikiLeaks Party have a realistic chance of winning seats in the 78-seat Senate.
Rudd was first elected prime minister in 2007, but was ousted in 2010 by his then-deputy, Julia Gillard, in an internal leadership showdown among Labor lawmakers.
He was dubbed "Recycled Rudd" by the media when he reclaimed the leadership in a similar challenge on June 26 as the government faced the prospect of a loss of historic portions with Gillard at the helm.
Since then, Rudd has changed several key policy positions, and opinion polls suggest Labor is closing the opposition's lead.
Nick Economou, a Monash University political scientist, said Rudd had been surprisingly successful in portraying himself as a new prime minister instead of the same leader who was once dumped by his colleagues.
"If Rudd can ram home that advantage, then Labor has got a chance," Economou said.
"The task for Abbott is to try to remind people that it's Rudd, he's the leader of a party that's been in government for a long time and is really at war with itself," he added.
A major policy difference is Abbott's opposition to charging polluters for their carbon gas emissions, despite Australia having some of the world's worst emission rates on a per capita basis. He has vowed to give priority to scrapping both the carbon and mining taxes.
Both taxes were introduced by Labor in July 2012. The carbon tax on Australia's biggest polluters rose from AU$23 a metric ton of carbon dioxide to AU$24.15 from July 1, 2013. The opposition argues this is the world's highest tax rate on carbon dioxide and is making Australian industry uncompetitive.