A Tory donor has registered a new party ready to champion a hard Brexit in a snap election amid rising concern that the Conservatives will eventually split over Theresa May’s strategy.

Jeremy Hosking, the multimillionaire financier who backed a series of pro-Brexit Tory candidates at the last election, said he had submitted the paperwork to form his new party, Brexit Express, which would welcome Tory MPs wanting to protest should the prime minister “botch Brexit”.

He made the move after launching a billboard campaign supporting a no-deal Brexit, claiming it was the only way of securing the right deal with the EU in the long term. Hosking said he expected many parties to be formed over the next year as “part of the reorientation of British politics”.

“Can these unhappy spouses co-exist in the same political party? The best form of defence is attack,” he said. “We don’t necessarily want the Tory party to split, but it seems to me that there is a good case for it.”

His decision follows the emergence of a series of pro-Brexit campaign groups to prepare for another referendum or contest European elections due to take place in May, after Britain is supposed to have left the EU.

It also comes amid heightened tension within the Conservatives, with many MPs wondering how the party will prevent a split before the next election. Mainstream Tories have turned up the pressure on the pro-Brexit European Research Group of MPs, many of whom condemned May to a Commons defeat last week.

Ministers and senior backbenchers are now openly warning that the ERG’s pursuit of a hard Brexit trumps its loyalty to the party. Tobias Ellwood, the defence minister, has said he does not regard the group as part of his party, while business minister Richard Harrington has said the MPs in the group are “not Conservatives” and should quit.

Former Tory minister Nick Boles is trying to rule out a no-deal Brexit. Photograph: Neil Hall/Reuters

There are also concerns that the Tory membership is tilting to the right as a result of Brexit. Margot James, the digital minister, warned that Nick Boles, a former Tory minister trying to rule out a no-deal Brexit, was facing “a deselection campaign prompted by Ukip entryism into his local Conservative Association”.

Conor Burns, a Tory MP and close ally of Boris Johnson, hit back. “Being pro-EU institutions and against the referendum result does not equal being liberal and decent,” he said. “Those claiming a battle for the soul of the party would perhaps be taken more seriously if they had been in the lobby voting for the most significant social reform in decades.”

Brexiters have been preparing for the possibility that Brexit is not delivered on time. A pro-Leave party has been registered to contest the next European parliament elections, should Brexit be delayed and Britain be allowed to field candidates. Nigel Farage has made it clear that he will use the Brexit party as the vehicle to stand as a candidate in such an eventuality. European elections take place in May, with the new parliament sitting from the summer.

Meanwhile, a cross-party group has already been preparing for a second referendum campaign by holding rallies under the “Leave Means Leave” banner. Former Tory leader Iain Duncan Smith, Labour MP Kate Hoey and Farage are among those to have taken part.

Esther McVey, the former work and pensions secretary, has also joined the cast list, alongside pro-Brexit businessman Tim Martin.

Farage uses the rallies to call on supporters to ready themselves for another battle. “Let us prepare, let us organise,” he said at one last month. “If I have to fight again against this lot, then believe me, next time, as far as I’m concerned, it’s no more Mr Nice Guy.”

Some veterans of the last Brexit campaign are even talking about an organised boycott should a second referendum take place, undermining any result to remain inside the EU.

Senior figures from the first official Vote Leave campaign are divided over what the next few months will bring. One said that they believed the chances of a second referendum had receded and that the next big battle would be over the Tory leadership. “Even if May gets a deal over the line, she will have to go soon after – there is no way the party will let her take charge of the future trade deal with the EU,” one said. “So that means a contest and probably an election before the end of the year.”