A group of Conservative councillors is refusing to campaign for the party in European elections in a protest against the government’s failure to leave the European Union.

Tories from Derbyshire county council have written to the party’s headquarters saying they will not deliver leaflets or canvass for the party’s candidates next month.

Councillor Barry Lewis, the leader of the council and the group, said he expected other Conservative councillors and activists to follow his group’s example.

It is further evidence of disillusionment and embarrassment among grassroots Tories over Brexit. Polls show the Conservatives have taken a huge hit after failing to take the UK out of the EU on 29 March or 12 April, or to come up with an alternative to Theresa May’s Brexit deal.

Lewis told the Guardian that every one of 37 councillors in the Tories’ group supported a proposal to boycott the EU election – even though it ran against their individual and collective instincts.

“We never thought we would ever have to do something like this. But this is about democracy and it is a form of protest. We are not going to deliver any literature pertaining to the EU elections,” he said.

“We had a very clear mandate and that date has gone by. If the national party does not show leadership and take us out of the EU, we will take matters into our own hands.”

He hoped the protest would help to shore up support in the local elections on 2 May. “Residents and supporters are angry, and think how they will feel when and if the polling card for the European elections hits the doormat just before the local elections of 2nd May.”

Lewis said he had written to the party’s chair, Brandon Lewis, on Thursday informing him of their decision but had received no response.

“I told Brandon Lewis that inviting Jeremy Corbyn, a Marxist, to the table in an attempt to pass a deal was in our view a serious mistake. It was the last straw,” he said. Two out of five MEPs in the East Midlands region, which includes Derbyshire, are Conservatives.

Nigel Farage’s new Brexit party has opened up a five-point lead in polling for next month’s elections to the European parliament. Photograph: Joe Giddens/PA

A YouGov European elections poll of 1,855 voters on Monday and Tuesday puts Nigel Farage’s Brexit party on 27%, followed by Labour on 22% and the Conservatives on 15%, though a high proportion of people said they did not know who they would vote for or that they would not vote.

Other Conservative activists are trying to press May to stand down as prime minister by forcing an extraordinary general meeting to allow a vote of no confidence from party members.

The vote would not be binding, but the national Conservative convention (NCC) would be obliged to hold the meeting if more than 65 Tory association chairs called for one.

The attempt has been organised by the Conservatives’ London East area chairman, Dinah Glover. The number of signatories has not been disclosed but Glover said she was confident of reaching the threshold imminently.

The motion drafted by Glover says the party “no longer feel that Mrs May is the right person to continue as prime minister to lead us forward in the negotiations”.

An extraordinary meeting of the NCC – the members’ body comprised of about 800 senior party officers – has never been called before and members would need at least 28 days’ notice of the meeting.

A spokesman for the party was approached for comment.

• This article was amended on 22 April 2019. An earlier version misnamed the East Midlands European parliament constituency as “Derbyshire”.