11.25PM: To summarise the day's events:

* Kevin Rudd has been elected leader of the Labor Party;

* Anthony Albanese is his deputy;

* Julia Gillard has resigned the prime ministership and will leave politics at the election;

* Independent MPs Tony Windsor and Rob Oakeshott will also leave;

* The Coalition wants an election as soon as possible.

* Tomorrow, Mr Rudd and Mr Albanese will visit Government House to be sworn in as prime minister and deputy prime minister.

10.45PM: Kevin Rudd has addressed the media, saying he "does not have it in his nature to stand idly by and allow an Abbott government to come to power in this country by default".

Mr Rudd said of Ms Gillard: "She is a woman of extraordinary intelligence, great strength and energy."

He also said the former Prime Minister faced difficult circumstances given the hung parliament.

Mr Rudd said were it not for "Julia" there would not be the better industrial relations and education policies that are now in place. Mr Rudd also paid tribute to Mr Swan, particularly the work they did together keeping Australia "out of a global catastrophe".

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9.35PM: Former deputy Labor leader Wayne Swan is now speaking. Mr Swan has stepped down as Treasurer. He has committed to contesting the next election.

The new deputy Labor leader is Regional Development Minister Anthony Albanese.

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9.15PM: Julia Gillard says she has written to the Governor-General asking her to commission Kevin Rudd as Prime Minister. 

"In the years in which I've served as Prime Minister, predominately I have faced a minority parliament and internal division in my party. It has not been an easy environment to work in

"I am very proud of what this government has achieved, which will endure in the long-term."

Ms Gillard said she was proud to be the nation's first female prime minister.

She lists the achievements she is most proud of - the price on carbon, education reforms, the introduction of DisabilityCare, the Royal Commission into sexual abuse of children in institutions and foreign policy achievements.

Julia Gillard thanked her colleagues for standing by her through all the speculation and media hype.

She said she understood that today "the pressure got too great".

"I respect that decision," Ms Gillard says.

Ms Gillard urged unity in the party and said Labor can win the next election.

"I know that it can be done, that it will best be done by putting the divisions of the past behind us and uniting as a political party."

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9.10PM: The following senior ministers have resigned from cabinet:

* Treasurer and Deputy Prime Minister Wayne Swan

* Communications Minister Stephen Conroy

* Schools Minister Peter Garrett

* Trade and Tertiary Education Minister Craig Emmerson

* Agriculture Minister Joe Ludwig

* Climate Change and Industry Minister Greg Combet

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9.05PM: Julia Gillard will address the media at 9.15 AEST. 

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8.50PM: Anthony Albanese has been elected deputy Labor leader, winning the ballot over Simon Crean, 61 votes to 38.

Gillard backers Trade Minister Craig Emerson, Communications Minister and Senate leader Stephen Conroy and Agriculture Minister Joe Ludwig have also resigned from the frontbench.

Climate Change Minister Greg Combet has also resigned from cabinet. 

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8.05PM: So let's summarise what has happened so far this evening:

Kevin Rudd has been re-elected leader of the Labor Party almost three years to the day since he was deposed by Julia Gillard.

Mr Rudd won the ballot 57 votes to 45. There was no spill for position of deputy leader however there are reports that Treasurer Wayne Swan has resigned. Simon Crean and Anthony Albanese are contesting the deputy leader position. 

He was elected after Ms Gillard called a ballot in a television interview on Wednesday following Fairfax Media reporting that supporters of Mr Rudd were circulating a caucus petition to allow a challenge for the prime ministership. 

It also came after Workplace Minister Bill Shorten made the dramatic announcement, less than 30 minutes before the ballot, that he had swapped his support from Ms Gillard to Mr Rudd.

Mr Shorten - who played a key role in the dumping of Mr Rudd as prime minister in 2010 - has been under sustained pressure in recent weeks to switch his allegiance.

It is unclear whether Mr Rudd will stick to Ms Gillard's schedule of a September 14 election or go earlier. The earliest date Mr Rudd can call an election for is August 3.

Ms Gillard retains the Prime Minister title until she visits the Governor-General Quentin Bryce and her commission is ended.

The result may spell the end of Ms Gillard's political career, with Australia's first female prime minister declaring earlier on Wednesday that she would not stand in the next election if she lost the ballot.

It is also expected that cabinet ministers Stephen Conroy and Peter Garrett will now quit the frontbench, as they have previously said they would do so if Mr Rudd was re-elected.

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7.55PM: Kevin Rudd has won the ballot 57 votes to 45. This means Julia Gillard has been dumped as Prime Minister and will not quit politics at the September election. There was no 'spill' for the Deputy Prime Minister position, however it's believed Wayne Swan will stand down from the role.

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7.15PM: There are reports Kevin Rudd would call a snap August election should he win tonight's ballot. There is also growing speculation Ms Gillard will lose the caucus vote. We'll bring you the result as soon as it's announced.

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7.00PM: Labor MPs and Senators are now in the caucus room. While you wait, why not take a look at what our readers think about Australian political leadership in our interactive Election 2013: Hot or Not? results page.

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6.40PM: Bill Shorten has announced he will back Kevin Rudd in tonight's vote, a significant indication Mr Rudd may win the ballot.

Mr Shorten said the decision may come at a "personal risk".

"The future of the Labor Party is at risk," Mr Shorten said

Kevin Rudd is the best chance the Labor Party has of winning the election, he added.

"Australians, regardless of their politics, want to see the Labor Party perform as best it can," Mr Shorten said.

"The best interests of the Labor Party must come first....not factions."

Mr Shorten said he would resign his ministry if Ms Gillard won and would serve in any capacity under Mr Rudd.

Mr Shorten did not take any questions

He will offer his resignation as a cabinet minister should Ms Gillard remain Prime Minister. 

Mr Shorten’s support for Ms Gillard had been seen as instrumental in helping her hold on to power. He is an influential leader of the Victorian Right faction, allied to Communications Minister Stephen Conroy and seen by many as a future Labor leader.

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6.30PM: Just 30 minutes remain until the leadership vote takes place. But many of you have already been busy voting by the looks of things. 

Our poll asking who you think should win the ballot has attracted about 1000 responses. About 30 per cent reckon Kevin Rudd deserves to emerge victorious. There's still time for you to join in. You can also have your say in the comments section at the bottom of the page.

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6.00PM: After confirming he will put his hand up to contest tonight’s ballot, Kevin Rudd is the $1.30 favourite with online bookmaker sportsbet.com.auto be the Labor leader on Thursday 27th and beyond.

Despite having overcome Rudd twice before, Julia Gillard is the outsider at $3.50, with any other candidate priced at $19.

“The betting indicates that today will finally be the day K-Rudd gets his revenge,” sportsbetcom.au's Shaun Anderson said in a statement tonight.  

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5.55PM: There are 102 members of the Labor caucus. Either challenger needs at least 52 votes to win.

However, a slim majority is bad news. Both Ms Gillard and Mr Rudd have said they would retire if they lost in order to end the saga. But winning by a small margin would demonstrate the division within the party.

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5.40PM: This will be the third Labor leadership ballot since the 2010 federal election.

In February 2012, Mr Rudd challenged Ms Gillard and lost 71 votes to 31.

In March this year, in response to a call from Simon Crean, Ms Gillard called a spill, but she was the only one to contest for the leadership.

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5.10PM: Kevin Rudd has said he will contest tonight's ballot.

Mr Rudd said Tony Abbott was on track to seize the Senate at the September election.

"We're on course for a catastrophic defeat unless there is change," Mr Rudd said.

"If I win this ballot every effort I have in my being will be to uniting the Labor Party. The values which drive our movement are those things which unite us."

Mr Rudd said he will not seek to punish his detractors.

"If I loose, of course I will announce I will not contest the next election and I thank Julia for making the same commitment."

Mr Rudd said he did  "not seek to fudge the fact that I have changed my position".

If he is successful, Mr Rudd said he will devote "every fibre" of his being to fight the Coalition.

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4.55PM: The Prime Minister has employed a similar tactic to the one she deployed back in February - bringing the ballot on quickly rather than letting numbers drift away over time.

It is a high risk strategy but, if the past three years have demonstrated anything, it is that Ms Gillard is not afraid of a fight.

The difference this time is that Ms Gillard has set the bar high for the loser - that he (because we all know who she is talking about) will leave politics forever and stop acting as a thorn in the side for whoever remains in control.

Tonight will be the third time the caucus has dealt with the party's leadership since the 2010 election (the previous occasions were February 2012 and March this year).

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4.45PM: We want to know what you think. Who will win the ballot, should Kevin Rudd be a contender? Have your say in our poll.

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4.30PM: Prime Minister Julia Gillard has called a ballot for the Labor leadership at 7pm on Wednesday and says she will stand.

Ms Gillard said that anyone who believed they should be Labor leader should put themselves forward in the ballot.

"There are no more opportunities, tonight is the night," she told Sky News.

Ms Gillard said that if anyone put their hand up tonight and lost, they should leave politics.

She said she hoped to lead the Labor Party following the ballot.

However, she said if she loses the ballot she will leave Parliament at the September election.

Ms Gillard said she would not be putting herself forward in Wednesday night's ballot unless she had a "degree of confidence" about her chances of success.

"The important thing is that people keep in their mind as they walk into that room, what's in the best interest for the nation?"

Ms Gillard's announcement comes after reports earlier on Wednesday that Kevin Rudd's supporters have started circulating a caucus petition to allow a challenge to Ms Gillard for the prime ministership.

"There is apparently a petition circulating within the Labor party ... I haven't seen this petition," the Prime Minister observed.

Ms Gillard further cast doubt over the petition's existence, likening it to the Loch Ness Monster.

She said that as a "rational" person she was aware of how "debilitating" the leadership talk was.

She said that whoever won tonight's ballot they could go to the election leading a united team.

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4.00PM: As another leadership drama grips Canberra, we think there's no better time to bring you the results of our latest election opinion poll, Election 2013: Hot or Not? 

This month's poll was focused on our pollies and parliament and some of the results are fascinating. In good news for the Rudd camp, the results don't make for happy reading for Ms Gillard or Mr Abbott.

Click the image below to see the full results

Some of the more quirky results: 

* When asked which of these well-known Australians our readers would most like to see enter politics, entrepreneur Dick Smith, retired defence chief Peter Cosgrove and banking supremo Gail Kelly rated highly. Poor old Eddie McGuire and Kyle Sandilands didn't do too well.

* About 50 per cent of respondents wanted to see an election fought between Julia Gillard and Tony Abbott. Just a fraction want an election between Kevin Rudd and Abbott.