Here are the contents of Crikey’s leadership live blog, which we kicked into gear soon after Simon Crean made his dramatic announcement just after 1pm. We start with the most recent posts first … 

5.17pm: Prime Minister Julia Gillard addresses the media in Parliament, saying she’s grateful to her colleagues and accepts their support “with a sense of deep humility”. “This has been settled, and settled in the most conclusive fashion possible,” Gillard said of the leadership issue. Deputy PM Wayne Swan also briefly addresses the media.

5.12pm: Like her or not, you have to give Gillard points for toughness, as SBS reporter Middleton points out on Twitter.

5.05pm: A pox on both their houses, says the effervescent Bob Katter:

Meanwhile, the media is starting to gather in Parliament’s austere Blue Room ahead of a press conference from Gillard at 5.15pm.

4.46pm: Julia Gillard remains PM. No one challenged her. ALP spokesman Chris Hayes has emerged from the caucus meeting to formally announce there was only one nomination each for the role of prime minister and deputy prime minister: Julia Gillard and Wayne Swan respectively.”Both were duly elected unopposed and unanimously by the parliamentary caucus,” Hayes said. “It puts beyond doubt the issue of leadership in the parliamentary Labor party.”

4.32pm: Gillard has just marched into the caucus room, flanked by a group of about 20 Labor MPs. It is certainly a show of support. She appears confident and so does her guard, which includes Labor MPs Wayne Swan, Kate Ellis, Stephen Conroy, Yvette D’Ath and Brendan O’Connor. “Hello, how are you,” Gillard says to the waiting media.

4.28pm: Influential ALP frontbencher Anthony Albanese has supported Rudd’s decision not to challenge for the leadership. “I believe Kevin Rudd has made the right decision in the party’s interest,” he told reporters. Albanese says he stands by his approach to never support a spill against a sitting Labor Prime Minister. Gillard will remain PM, he says.

What a situation! Has Crean gone off half-c-cked? Will anyone challenge at the caucus meeting, starting any second?

4.21pm: Kevin Rudd has just faced the media to announce he will not stand in the leadership ballot. Flanked by supportive colleagues in the corridor of Parliament House, Rudd said this:

“I believe in honouring my word … The only circumstances under which I would consider a return to leadership is if the overwhelming majority of party requested my return and the position was vacant. Those circumstances do not exist. I will be adhering to the commitment I gave to the Australian people and to my colleagues … I take my word seriously. I gave it solemnly in that room after the last ballot. I’m not prepared to dishonour my word … I will therefore adhere to that word.”

Rudd called on the party to unite to ensure Tony Abbott did not walk into the Lodge.

4.16pm: Labor MPs are expected to start filing into the leadership spill any minute. Meanwhile, spare a thought for the people affected by the forced adoption of children in the 20th century. They received a heartfelt and long-awaited apology from Julia Gillard and Tony Abbott this morning, but that’s been eclipsed by the spill.

3.40pm: We still don’t even know if Rudd will nominate for leader at the spill at 4.30pm. This update from ABC reporter Latika Bourke:

SkyNews reckons the following Labor MPs have been spied in Rudd’s office: Ed Husic, Tony Zappia, Richard Marles, Stephen Jones. Confusion reigns in Parliament House. Normally MPs would be getting ready to head to the airport and leave Canberra as the sitting week wraps up. Not this time. They’re frantically phoning around and changing their flights.

3.25pm: Sportsbet has Rudd the frontrunner at $1.30 with Gillard at $3.00. But she’s fighting back — she was at $6.00 half an hour ago. And she just now dropped to $2.80.

And she’s got this vote sewn up — outspoken Labor MP Steve Gibbons tweets this (Gillard’s winning the race on Twitter FYI):

3.11: Treasurer Wayne Swan weighs in. He is highly likely to go down with Gillard should she lose today’s ballot.

2.56pm: Bernard Keane writes:

Question time has come and gone, with an attempt by the opposition to suspend standing orders to move a motion of no confidence failing. The motion was supported by independents Rob Oakeshott, Tony Windsor and Andrew Wilkie but failed to achieve the necessary absolute majority of the House.

A motion of no confidence — Opposition Leader Tony Abbott’s first — may not have been particularly interesting given Gillard remains Prime Minister and thus her agreements with Oakeshott and Windsor remain in place. Wilkie has indicated he will only vote no confidence in the case of a major scandal. The Prime Minister’s speech in response to Abbott’s motion to suspend remarks contained little of her usual back-against-the-wall fire, but relied on outlining her achievements and warning that she had more left to do.

Meantime the counting game is on in earnest, with attention focusing on how many numbers Simon Crean can bring over to the Rudd camp, estimated to be no more than 35-40 MPs. The problem for Gillard is that a victory will do nothing to address Simon Crean’s defection or the persistence of a core of Rudd supporters of around a third of the caucus.

Crean’s office has confirmed to reporters he has been sacked from all ministerial responsibilities. When he faced the media earlier he said he wanted to stay on as minister for arts and regional affairs, but he hasn’t got his way. No word on a replacement.2.42pm: Julia Gillard has shut down question time after Abbott’s move to have a no-confidence motion in her failed.

There were 73 votes to suspend standing orders to hold the no-confidence motion, 71 against; the motion required an absolute motion to get up, so failed. Worth noting that key independents Andrew Wilkie, Rob Oakeshott and Tony Windsor voted “yes”. Does this bode ill for whoever wins the leadership ballot? Would the independents push them to a swift election?

Media commentator and Liberal expert Peter van Onselen tweets:

2.25pm: Tony Abbott, in question time, tells Gillard:

“I say to the current Prime Minister, for your party’s good you should go. For your country’s good, you should go.”

Gillard is now firing back at Abbott. Note that Kevin Rudd is in the chamber, as is Simon Crean; but Crean has gone to the backbench after precipitating today’s dramatic events.

Remember the last time this happened, when Rudd and Gillard faced off in February 2012? Key Rudd supporters were Anthony Albanese, Martin Ferguson, Chris Bowen and Kim Carr. Penny Wong, Tanya Plibersek, Wayne Swan, Stephen Conroy and Simon Crean all backed Gillard. Crean has now shifted — and who else?

2.17pm: We’re in question time. Tony Abbott has moved a no-confidence motion in the PM, and is listing what he says is a litany of Labor failures. Meanwhile, Labor MPs have started to tweet how they’ll vote. Here’s ACT Senator Kate Lundy:

2.04pm: News Limited journalist Phillip Hudson tweets:

2.01pm: Prime Minister Julia Gillard tells question time there will be a ballot for the leadership at 4.30pm today. She seems determined and defiant.

Her dramatic announcement follows Labor frontbencher Simon Crean’s call, made to the media just after 1pm today, for Gillard to hold a leadership spill. Crean said he’d run for deputy, and supported Kevin Rudd running for leader — although it’s not clear at this stage if Rudd will even run.

Up-and-coming Labor parliamentary secretary Richard Marles went on SkyNews to support Rudd as leader. These kinds of appearances can be quite influential; remember union big-wig Paul Howes going on TV before Gillard rolled Rudd in June 2010?

1.45pm: Bernard Keane writes:

Labor frontbencher and former leader Simon Crean has pulled the trigger on the Labor leadership crisis, calling for Prime Minister Julia Gillard to spill all leadership positions and backing Kevin Rudd with himself as deputy leader.

Crean’s intervention comes as the climax for an extended leadership dilemma for Labor, with Rudd’s camp unable to muster the numbers to defeat Gillard despite a dreadful start to the year in the polls.

However, there are important process issues to be addressed. Crean has indicated he doesn’t expect the Prime Minister to accept his plea to spill leadership positions, in which case it will be up to her opponents to muster the 35 votes to successfully call a spill in caucus via the caucus chairman before MPs leave tonight (prospects of Parliament sitting tomorrow have evaporated with the withdrawal of the media reform bills).

Crean, who has been a strong supporter of the Prime Minister, said he wanted a circuitbreaker for the continuing destabilisation and that Labor’s problems would not be solved by simply swapping leaders. Labor needed to demonstrate it believed in something, he said.

The move by the former leader (and persistent critic of Rudd) breaks the impasse Labor found itself in with the Rudd camp unable to muster anywhere near sufficient numbers to defeat Gillard and Rudd himself repeatedly, in private and in public, saying he would not challenge under any circumstances. With a leadership spill initiated by Crean, Rudd now has the chance to stand; indeed, there is no way Rudd can avoid standing.

Crean also portrayed himself as a deputy capable of ensuring Rudd, whose wretched management style was one of the key reasons for his downfall in June 2010, would be a more inclusive leader if he takes over again as prime minister. That has been a persistent problem for Rudd backers, with the memory of Rudd’s behaviour as leader still strong in many backbench minds, as well as being a reason why a number of cabinet ministers indicated either publicly or privately they could not work with him again.

Crean also ruled out seeking the treasurership, which has long been rumoured to be promised to the New South Wales Right’s Chris Bowen, who backed Rudd last February and is his highest-profile ministerial backer.

There are disputed media reports that the NSW Right will back Rudd, which combined with Crean’s support would make Rudd very difficult to stop in a leadership contest. Crean has said he wishes to retain his ministerial position pending the outcome of the current contest.