As many as 80 of her MPs are set to reject May's Brexit plan, according to Baker | Jack Taylor/Getty Images Tory party faces ‘catastrophic’ Brexit split, says former minister Steve Baker, who resigned over Theresa May’s Brexit strategy, says up to 80 MPs are likely to resist the plan.

The U.K. Conservative Party will suffer a "catastrophic split" if Theresa May pursues her Brexit plan, according to a former minister who said as many as 80 of her MPs are set to reject it.

Steve Baker, who quit as a junior Brexit minister following the agreement on the plan by the Cabinet at the prime minister's Chequers country residence, told the Press Association that he expects a showdown at the party's conference, which begins later this month.

"We are reaching the point now where it is extremely difficult to see how we can rescue the Conservative Party from a catastrophic split if the Chequers proposals are carried forward," he said.

He said he hopes Tory members at the conference would unite "around the idea that we can either leave having accepted the EU offer or we have to leave with nothing agreed." He wants to shift the government toward negotiating a Canada-style trade deal with the EU.

But David Gauke, the justice secretary, told the BBC's Today program that MPs should get behind the prime minister. "There isn't an alternative credible plan out there," he said.

Separately, Boris Johnson, the former foreign secretary and standard bearer for Brexiteers, used his weekly Daily Telegraph column to further burnish his leadership pitch with a call for lower taxes.

"We should say that tax henceforward will not go up. That’s it. No new taxes and no increase in rates," he wrote.