Julia Gillard announces Australian election date. Reuters

Julia Gillard, the Australian prime minister, has announced a general election will be held on 14 September, surprising the electorate and ending speculation about when she would take her minority government back to the polls.

The announcement by Gillard, Australia's first female prime minister, kicks off what some commentators have described as the longest election campaign in history. The poll will mark the end of a divisive hung parliament in which the Labor government has survived on the support of independent and Green party members of parliament.

Gillard, stunning the media contingent during an address at the National Press Club in Canberra, said her intention in calling the election so far out was to give certainty.

"Announcing the election date now enables individuals, investors and consumers to plan their year," she said. "It gives shape and order to their year. "I do this not to start the nation's longest election campaign: quite the opposite. It should be clear to all which are the days of governing and which are the days of campaigning."



Parliament will be dissolved on 12 August. It is the first time any prime minister has given such long notice for an election. Australia's federal term of government runs for three years. The latest date Gillard could have gone to the polls was in November.



Gillard said the election date allowed for the year to be one "not of fevered campaigning but of cool and reasoned deliberation". She said no surprises about the election date should mean "no excuses", a clear barb at the conservative opposition leader, Tony Abbott, whom she has criticised as announcing "platitudes not policies" and giving few costings for his promises.



"Australians are not interested in campaigns without content, [in] platitudes devoid of purpose," she said.



Gillard said she had made the announcement to allow all parties to have the chance to properly cost their policies.



The conservative opposition leader, Tony Abbott – whom Gillard accused of sexism and misogyny in a fiery speech to parliament last October – welcomed the announcement, saying his party was "so ready".



"This election will be about trust," he said. "Who do you trust to reduce the cost of living pressures? Who do you trust to boost small business security? And who do you trust to secure our borders?"



Since Gillard won the 2010 election by the slimmest of margins, Tony Abbott has painted her as someone who can't be trusted, in large part because of her promise before the poll not to introduce a carbon tax. Introducing carbon pricing later became part of her deal with the Green party to take power in a minority coalition.



In a three-minute television appearance Abbott said the choice between the two parties was clear. "It's more tax or less. It's more regulation or less. It's less competence or more. It's less freedom or more."



He used the word "positive" five times – an attempt to cast off the image the government has painted of him as a person who says no to everything it does.

The Australian Broadcasting Corporation's elections analyst, Anthony Green, said the announcement was designed to put pressure on Abbott to start "releasing some policies and not putting it off to the never-never".



The election date has been welcomed by the Green party whose single MP in the lower house of parliament has helped keep Gillard in power. Two of the independents who have also kept Labor's minority government afloat, Tony Windsor and Rob Oakeshott, also welcomed today's announcement.



The announcement of an election date appears to have dampened speculation that Kevin Rudd – the man Gillard ousted from the top job three years ago – will mount a leadership challenge, something that has dogged Gillard's term as prime minister. At times she has suffered record unpopularity.



"I think now we are in an election year, it's less and less likely that we're going to see a change at the top. I think it's up to the Labor party to get behind the leader," Bruce Hawker, longtime Labor strategist and the man who ran Rudd's challenge against Gillard last year, told ABC TV.

Recent polls suggest the election in September is likely to be a close-run contest. According to a Newspoll carried out for the Australian newspaper two weeks ago, the opposition is marginally ahead 51% to 49%.



Both Gillard and Abbott remain unpopular as leaders, though Gillard leads Abbott as preferred prime minister by 45% to 33%, according to Newspoll.



Key issues that have featured in the run-up to Gillard's election announcement have been economic management, border security and a national carbon pricing regime introduced by her government to combat global warming.