THERESA MAY and Jeremy Corbyn are experimenting with hazardous materials.

They are seeing if they can create a Tory/Labour Brexit compound without blowing up their own parties.

6 Credit: The Sun

Those in the talks are more optimistic than ever about ­getting some kind of agreement, if not a finalised deal.

But they know that things are very volatile.

One senior figure tells me things are “much better than people think, but could blow up at any time”.

What is causing this Downing Street optimism is a sense that there is beginning to be pressure on Labour to do a deal.

Look at the council seats they lost in Leave-voting areas and the progress Nigel Farage’s Brexit Party is making in ­Labour regions ahead of this month’s European elections.

I understand that the ­compromise being drawn up goes as follows.

The UK would initially enter into a “comprehensive customs arrangement” with the European Union.

This would be very similar to a customs union.

But the two parties would then commit, and hope to persuade the EU to do the same, to there being two choices for the future — either an independent trade policy under a scheme similar to the facilitated customs arrangement that May proposed at Chequers or a customs union with a UK say over future trade deals, which is Labour’s policy.

A LEAP INTO THE UNKNOWN

The irony of this is that the EU has not said that it will accept either of these options.

Getting Brussels to include them in the political declaration will not be easy.

The Prime Minister’s chief of staff, Gavin Barwell, has told Tory MPs that about half the stuff that Labour has asked for in the talks — on subjects such as co-operation with EU agencies and crime — are things the Government has already tried to get from the EU.

There would also be a separate bill that would put the UK on course to remain in “dynamic alignment” with the EU on workers’ rights. I am told that the bill will be “more dramatic” than Tory MPs would like.

6 Theresa May has failed to convince the EU so far Credit: AFP

The big risk May is running in trying to cut this deal is how her own party will react to an arrangement with Labour.

One senior Cabinet minister has told colleagues that he fears co-operating with Corbyn ­legitimises the Labour leader and that he would rather resign than back a deal.

Those close to this secretary of state argue that in these ­circumstances, it would be ­better for the Tories to argue for a new deal with the new EU ­Commission, which will take office in November.

But others in Cabinet think that without a General Election — which the Tories are in no ­position to fight — there is no way to deliver Brexit without a deal with Labour.

One calculates that while many Tory MPs would not vote for it, they would not cause a permanent split in the party over it.

6 Jeremy Corbyn's Labour have no clear Brexit policy Credit: Alamy Live News

On the Labour side there are, perhaps, even more ­substantial obstacles to a deal.

A huge number of Labour MPs, including pretty much the whole whips office, want a ­second referendum.

If Britain’s MEPs are not to take their seats in the new EU parliament, the Withdrawal Agreement bill will have to be introduced to the Commons in the next two weeks.

This is, I understand, Downing Street’s deadline for these cross-party talks to reach a conclusion.

A Labour/Tory agreement would require both May and Corbyn to be prepared to risk splitting their parties.

This may seem unlikely BUT this week’s elections show that both parties are paying a price for failing to get Brexit done.

PM Theresa May says voters' message from local election results is, 'Get on and deliver Brexit'

Vote sparks new ballot fears

WHAT’S the main lesson from this week’s local elections?

Neither major party could be confident of how they’d do in a General Election.

The result for both the Tories and Labour was poor.

6 Farage is coming... the main parties need to get their act together Credit: AFP

If this had been a national election, both would have got less than 30 per cent of the vote.

Remarkably, these numbers flatter the two ­parties. The Tories – in particular – benefited from the fact that the Brexit Party weren’t standing in these elections.

But the results also indicate something else: Everything is to play for in British politics.

The Tories have clearly exasperated voters with their handling of Brexit.

But Jeremy Corbyn’s ­Labour hasn’t sealed the deal yet either.

The task for the next Tory leader is clear.

They need to get Brexit done to halt Nigel Farage’s Brexit Party and they need to persuade those affluent voters ­backing the Liberal Democrats that a vote for ­anyone but them at the next election is a vote for Corbyn and the higher taxes he represents.

Javid must win crime battle SAJID JAVID told a private meeting of Tory MPs on Wednesday evening that his top ­priority for the coming spending review is to secure more money for the police. Javid’s mission is a recognition that police cuts – and the sense that crime and anti-social behaviour are rising as a result – is hurting the Tories. I am told that in focus groups, traditional Labour voters say they worry that Corbyn is soft on crime. But they think the Tories aren’t any better, so there’s no point changing their vote on the issue. If Javid wants to show the Tories that he’s the right man to take on Corbyn as a future PM, then winning back the party’s reputation on crime would be the way to do it.

Time for clarity on May's exit plan

6 Theresa May needs to make clear what her Brexit plan actually is Credit: PA

I UNDERSTAND that Conservative Campaign Headquarters indulged in some serious arm-twisting to try to stop a grassroots vote of no confidence in Theresa May’s leadership.

Association chairmen who were backing the push but also want to be Conservative candidates were told in no uncertain terms that this would hurt their prospects.

But this was not enough to stop the challenge.

It is a reminder that the current situation with Theresa May only saying that she will go when a Brexit deal passes is not tenable.

Number 10 has argued that May couldn’t provide more details on her departure plans before the local elections.

But now they are out of the way, she should.

I understand that one member of the Tory parliamentary party’s ruling executive – the 1922 Committee – has already told colleagues that he has changed his mind and would now favour a rule change to allow a challenge to May if she does not do so in the next three weeks.

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Nothing marginal about by-election

6 Fiona Onasanya's removal as a MP has prompted a by-election Credit: PA:Press Association

THE Peterborough by-election on June 6 will be the most important one since the country voted for Brexit.

This is a Labour/Tory marginal with a 61 per cent Leave vote.

Neither of the main parties are in a good position to fight it.

Labour are damaged by the fact the by-election has been caused by the criminal conviction of its ousted MP, Fiona Onasanya.

The Tories by their Brexit failure.

The Brexit party are having a big rally in Peterborough on Tuesday and will not announce their ­candidate for the by-election before that.

But they expect to have one in place by the end of next week.

If there is a cross-party deal on Brexit by June, this by-election could be the first significant test of public opinion on it – and whether a deal deflates the Brexit Party or gives it more oxygen.

- James Forsyth is Political Editor of The Spectator.