Nicky Morgan has blamed the language used by some vehement Conservative Brexiters of helping to inspire threats against MPs, as Theresa May prepares for the return of parliament against a backdrop of renewed plots to depose her.

Amid signs that Tory MPs will be no more united on Brexit when the Commons returns on Tuesday than before the Easter recess, Morgan, the former education secretary, criticised an article by her backbench colleague, William Cash.

Writing in the Daily Telegraph, Cash, a leading member of the European Research Group of strongly pro-Brexit Conservatives, accused May of having made an “abject surrender” to the EU, talking also of “appeasement” and “capitulation”.

Cash wrote: “How low can we sink with the prime minister making us crawl on our hands and knees, not only to the EU, but to Germany and France?”

Speaking on BBC Radio 4’s Today programme, Morgan condemned the article, saying: “This kind of language is not helpful. It’s not the kind of language that our councillors, or frankly any normal people, would use.”

Asked whether she saw any connection between such phrases and the threats received by some MPs, Morgan replied: “Yes, I do.” Such comments, she said, were “stoking up other people who are often sitting at home and watching this stuff, and it gets them really, really angry and fired up, and then they will say things that they would never say face to face”.

Morgan urged Conservative MPs to return from Easter and swiftly agree a Brexit deal: “The focus really has to be on trying to nail down the terms of our withdrawal from the EU as soon as we possibly can.”

However, there were few signs of a breakthrough, even with talks between the government and Labour scheduled to resume next week. One report said May would lead new talks, but Downing Street did not confirm this.

Considerably more energy seems to be being expended on plots to remove May, especially if local elections a week on Thursday result in significant losses for the Conservatives in councils where they tend to do well.

According to the Telegraph, the Tory party group representing grassroots members will be forced to call an emergency meeting to hear a no-confidence motion in May after enough local party chairs signed a petition supporting the move.

Such a vote by the National Conservative Convention would be symbolic, but it would give renewed impetus to Tory MPs who hope to change the formal leadership rules to allow them an early chance to oust the PM.

The current rules allow such a formal challenge only once a year, and May won a confidence vote among her MPs in December.

One senior local Tory member explained on Monday that frustration over the Brexit deadlock meant she and local colleagues would not campaign for the party before the local elections.

Carol Hart, a member of Derbyshire county council, told Today the mass decision had been made “with a very heavy heart”.

She said: “But that fact is that people across the country, not just in Derbyshire, are all absolutely sick to death of the way this is going on, and it’s having a major impact on our reputation.

“We work as a group – we don’t always agree. But usually we talk behind closed doors, we do try and reach a compromise. You do have to compromise sometimes and I think it’s just such a big mess.”