A row between a Birmingham Labour MP and an ally of Labour leader Jeremy Corbyn kicked off a week of chaos for the official opposition.
But this was just one of a number of issues this week causing deep division within the party.
Others included a U-turn over whether to back elements of the Government’s spending plans and disagreement over immigration policy.
The most contentious division was sparked by backbench Labour fury about the creation of a new left wing campaigning body called Momentum, which is apparently designed to help Mr Corbyn strengthen his grip on the party.
Ms Phillips and Ms Abbott have a history of bad blood, and had an altercation in Parliament in September when Ms Phillips claims to have told her rival to “f*** off”.
The latest disagreement came after Yorkshire Labour MP Jo Cox called for military action to help victims of ISIS in Syria, in a joint article with Birmingham MP Andrew Mitchell (Con Sutton Coldfield).
Ms Abbott took to Twitter to criticise Ms Cox, as well as Cumbria MP John Woodcock, a vocal critic of Mr Corbyn.
Naming the two Labour MPs, she said: “So these people want to join with the Tories & vote to bomb Syria”.
Ms Abbott is a member of Labour’s Shadow Cabinet, and a political ally of Mr Corbyn.
It means her words carry weight – and accusing fellow Labour MPs of being “like the Tories” is a cutting attack in Labour circles.
Ms Phillips publicly leapt to the MPs’ defence, declaring on Twitter: “Good to see I’m not the only new MP who’s opinion (which takes bravery to speak up) is being silenced by Diane. WTF”.
She added: “Seriously Diane I was raised by socialists I am a socialist, Did you forget it is about kindness & tolerance #sad”.
And in a further dig at Ms Abbott she added two minutes later: “I don’t know if anyone noticed but I have made a career and a life standing up to bullies.”
Mr Corbyn has promised a “gentler politics” and repeatedly promised to make policy decisions through open debate within the party.
So it seems bizarre that a member of the Shadow Cabinet chose to attack Labour MPs who expressed an opinion on a difficult topic like Syria.
But worse than that, it appears that even the two most senior people in the Labour party can’t quite agree on the issue.
John McDonnell, the Shadow Chancellor and the person seen as closest to Mr Corbyn, said at the Labour conference: “On the Syria thing it should be a free vote”. But Mr Corbyn’s staff say the leader has never agreed to hold a free vote on military action. Then there was Labour’s U-turn over support for the government’s fiscal charter.
Mr McDonnell originally said Labour would vote for this, on the grounds that it would prevent the Tories branding the party “deficit deniers”.
He then announced that he had “changed my mind on the parliamentary tactics”.
BBC journalists reported Mr Corbyn had “no idea” the U-turn was coming.
There are also reports that Labour MPs privately called on Mr Corbyn to support the Government’s immigration bill, which includes measures said to prevent immigrants undercutting British workers.
But most damaging of all is anger over the way that Mr Corbyn’s leadership campaign has continued operating since he became leader – even though it seems to back Mr Corbyn personally rather than the Labour Party. The campaign has re-named itself Momentum and is urging people sympathetic to Mr Corbyn to sign up.
Critics see it as a way of mobilising the people who backed Mr Corbyn in the leadership battle, to help him control the party and silence opposition.
The group, which has a website at peoplesmomentum.com, says its aim is to “encourage those inspired by Jeremy Corbyn’s campaign to get involved with the Labour Party”.
Matters came to a head at a meeting of the Labour MPs in a Commons committee room, when Leeds MP Richard Burgon – another ally of Mr Corbyn – attempted to defend the Momentum campaign.
One of the MPs at the meeting said: “That is when it all descended into chaos. Richard Burgon was just howled down.
“I have never seen anything like it. People were just shouting at each other across the aisle. It was like a student union.”
The saga of Jess Phillip’s arguments with Abbott provides good copy for Westminster journalists. But it’s a symptom of a deeper problem within Labour, involving chaotic leadership and lack of trust between Mr Corbyn’s supporters and the rest of the party.