ITV News' political correspondent, Carl Dinnen, reports.
As pressure on Jeremy Corbyn to resign increases, the Labour leader has released a video message to party supporters, urging them to "come together".
However, this is at the same time that Labour's deputy leader Tom Watson has said that on Tuesday he will speak to the unions to try and get them to withdraw their support for Mr Corbyn.
Former shadow cabinet member Anglea Eagle has also said she has "the support to run and resolve this impasse", and that she will do if Mr Corbyn "does not take action soon".
The Public and Commercial Services (PCS) union has agreed that it will back Jeremy Corbyn against other contenders for Labour leader.
The union's ruling body also agreed to step up anti-racism campaigning at an emergency meeting to discuss the fall-out from Brexit and how it impacts on its members' jobs.
At the meeting, members noted that Mr Corbyn had promised to restore national pay negotiations in the civil service and oppose further cuts to pay and redundancy terms, and to repeal the Trade Union Act.
PCS general secretary Mark Serwotka said: "Our union supports Jeremy Corbyn against what is clearly a choreographed and undemocratic attempt to unseat him.
"Using the EU referendum result as cover is inexcusable when the urgent need is for Labour and the unions to unite to combat the rise of racism."
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Labour’s shadow business secretary Chuka Umunna has described the government's trade union reform plans as " the latest in a long line of attempts to stifle reasonable democratic scrutiny, protest and challenge".
He said: "The bill tries to drive a false wedge between government, industry, employees and the public by restricting rights – and at worst criminalising – ordinary working people, from midwives to factory workers to challenge low-pay or health and safety concerns.
“After muzzling charities and restricting access to justice this is the latest attempt to silence critics of this government and its policies.”
Yvette Cooper, one of Labour's leadership candidates, said that the government's plans for trade unions are an "ideologically driven attack on Britain's trade unions" which "puts narrow Tory party interests ahead of what is right for the country".
"It not only undermines years of progress on workers' rights, but it also breaks the growing consensus on the need to reform funding of political parties.
"This is another example of the Tories employing cheap divide-and-rule tactics."
The government's plans to make strikes harder to organise has been criticised as a "brutal assault on the most basic of human rights" by Mick Cash, the leader of the RMT.
He also said that the government's plan "mirrors the actions of hard-right regimes throughout history".
He added: "The trade union movement will unite to fight this brutal assault on the most basic of human rights and that campaign will be taken into the communities who stand to lose access to safe and reliable services as this noose of the anti-union laws is twisted round our necks."
Len McCluskey, the general secretary of Unite has categorically denied that unions are considering disaffiliating from Labour.
"This idea that we are considering disaffiliating from the Labour Party is nonsense," he told ITV News political correspondent Emily Morgan today.
He added: "In many ways the Labour Party has never been as united as it currently is."
Jim Murphy launched a broadside attack on Unite boss Len McCluskey as he announced he will resign as leader of the Scottish Labour party.
Mr Murphy said that while trade unionists were "a source of enormous strength and moral purpose" to Labour, the party should not be beholden "to one man."
One of the things about stepping down is that you can say things in public that so many people in the Labour party only say in private. So whether it's in Scotland and the contest to come across the UK. We cannot have our leaders selected - or de-selected - by the grudges and grievances of one prominent man.
The leader of the Scottish Labour party doesn't serve at the grace of Len McCluskey. And the next leader of the UK Labour party should not be picked by Len McCluskey.
A union has welcomed Conservative plans to give emplyess three days paid leave to take part in voluntary wor.
The TUC said that members would be able to use the time to get more involved in their union.
The TUC has long called for a Community Day Bank Holiday to encourage volunteering and community engagement. We therefore welcome any move that makes employers recognise the benefits of volunteering and social action.
Trade unions are the UK's biggest voluntary groups. This new right will give every union member a guaranteed three days for time off to get involved with union activities.