BORIS Johnson has ripped into Theresa May today as he kickstarts his leadership bid to become Prime Minister.

The Brexiteer used a barnstorming speech this morning to rally the country in favour of leaving with a clean break following Theresa May's defeat earlier this week.

6 The Tory Brexiteer launched a rallying cry today to truly deliver Brexit Credit: AFP or licensors

But he said there should be one final push to Brussels first to demand they scrap the hated Northern Irish backstop now - or we WILL walk away.

The Brexiteer blasted the PM for not even asking the EU to ditch it, saying she needed to "mean it this time" when she went back to them.

And he attacked her agreement for bending to Brussels' rules and tying us to them by the "apron strings".

In a speech putting him front and centre of the leadership battle to come, he also vowed not to raise new taxes and promised to spend more money on public services to bring Britain back together again.

His major intervention came just minutes after Tory Brexiteer Penny Mordaunt launched a fightback against Remainers in the Cabinet urging the PM to go for a softer Brexit.

The International Development Secretary defended leaving with No Deal and said that not honouring the result of the referendum would be "appalling".

She even said the upsides of leaving "outweigh" the downsides of staying - after a Question Time audience last night cheered the prospect of No Deal.

As Mrs May spends another day trying to work out what to do with Brexit:

Whitehall chiefs are on alert for another election within weeks

Jeremy Corbyn faces the threat of resignations from his top team if he u-turns and backs a second Brexit vote

The PM spoke with Angela Merkel earlier and will hold further talks with MPs and leaders over the weekend

Boris said this morning that there would be "challenges" of leaving without an agreement in place on March 29.

But he said that everyone in Britain knows "we are more than up to it".

"We have got so far, we must not give up now," he vowed, urging the PM to go back one final time to demand changes, strengthened after MPs rejected her deal overwhelmingly.

"If we hold our nerve we will not deliver this fake Brexit, but the Brexit people voted for.

"If we mean it, if we are determined, and if we make it clear that this is our best and final offer, I would be amazed if we cannot get agreement on these terms."

A poll of Sun readers last night showed that half of them want No Deal.

We've come so far, we must not give up now Boris Johnson

Boris said it would be "shameful" to extend Article 50 and push Brexit day back as dozens of MPs are demanding.

"To extend Article 50 now would do nothing but erode trust in politics," he warned.

"It's overwhelmingly likely that we will get a deal, we will get a good deal, but we won't leave with this deal."

In a thinly veiled leadership pitch today Boris said leaving the EU was a chance to finally unite the country.

And in a bid to woo over Tory members who could vote him to be the next party leader and Prime Minister, he promised to introduce no new taxes.

The Tory heavyweight said: "This is not because we want to create a tax haven for the rich.