THERESA May has refused to rebuke Boris Johnson despite the Foreign Secretary calling the Prime Minister’s Brexit plan “crazy”.

Downing Street even went as far as to say the Tory leader still had full confidence in Johnson. But as much as May might want to slap down her Brexiteer colleague, she could be too weak to do so.

Johnson’s revolt came as May’s Brexit Repeal Bill suffered its 13th defeat in the House of Lords.

Peers backed plans to keep the UK in the European Economic Area, and remove the reference in the EU Withdrawal Bill to exit day being March 29, 2019.

May will now need to try to have that overturned in the House of Commons. But that will be the least of the Prime Minister’s problems.

Her Cabinet is still openly divided on the UK’s relationship with the EU after Brexit and how that relationship needs to avoid a hard border on the island of Ireland.

Johnson took to a daily newspaper to savage May’s preferred option of a post-Brexit customs partnership.

That arrangement would see the UK collect customs tariffs on behalf of the EU.

It also means having some form of regulatory alignment to the customs union, which Brexiteers think will delay Brexit.

The National:

Johnson told the paper that May’s plan would create a “whole new web of bureaucracy”, would not comply with promises to take back control, and would hamper the UK’s ability to strike trade deals.

“It’s totally untried and would make it very, very difficult to do free-trade deals,” he said.

“If you have the new customs partnership, you have a crazy system whereby you end up collecting the tariffs on behalf of the EU at the UK frontier.”

That earned Johnson the approval of Jacob Rees-Mogg, the influential leader of the Tory Brexiteers.

“Boris hits the nail on the head,” Rees-Mogg tweeted.

He told another daily newspaper that he thought Johnson would be a tougher Prime Minister than May.

One senior Tory source was quoted in another newspaper still that Boris’s remarks were “a declaration of war.”

Asked if May has full confidence in Johnson as Foreign Secretary, the PM’s spokesman said: “Yes.”

He added: “There are two customs models that were put forward by the Government last August and most recently outlined in the Prime Minister’s Mansion House speech which the entire Cabinet was signed up to.

“Following last week’s sub- committee meeting, it was agreed that there are unresolved issues in relation to both models and that further work is needed.

“The Prime Minister asked officials to take forward that work as a priority.”

Johnson favours the second option being discussed by the Cabinet, known as Maximum Facilitation.

This involves new, as yet unavailable and possibly uninvented, technology to reduce friction at the border between the north and south of Ireland.

Both options being discussed by the Tory Cabinet have already been rejected by Brussels.

Former attorney general Dominic Grieve said that Johnson’s decision to speak out was “regrettable”, but said he could understand why May was willing to put up with his “outbursts”.

Grieve told BBC Radio 4’s World at One: “I don’t think he is in any way inhibited by normal propriety in government.

“I can well understand that seeing the difficult issues that we are having to confront, which are very divisive, the Prime Minister should accept these rather extraordinary bursts of misbehaviour by Boris.”

Meanwhile, in Ireland, Brexit has, if anything, heightened pro-European sentiment, with a new survey showing that 92% of the population support staying in the EU.