The Prime Minister is being urged to scrap the Chequers deal by senior Conservative officials in Kent, who say the party is falling short of its Brexit pledge.

The chairmen and deputy chairmen of seven local constituency associations have signed a letter calling on Mrs May to abandon the deal.

The letter is highly critical of the plan, saying it fails to deliver what the party committed to during the referendum campaign and in its manifesto at the general election a year later.

They say there is widespread discontent within the party as the deal does not meet the red lines set out by the Prime Minister – namely leaving the single market, the customs union and the European Court of Justice.

It says: “We call on the Prime Minister to recognise the discontent over Chequers that is felt by parliamentarians, as well as party officers, activists, ordinary members and the general public, and to join us in pledging to stand up for Brexit by looking at alternatives to Chequers that respect the red lines and offer an ambitious and positive global future for our country.”

The letter published in the Daily Telegraph is signed by more than 40 constituency chairmen.

The signatories from Kent include Lynne Connolly, chairman of South Thanet Conservative Association and Paul Cooper, deputy chairman of the Faversham & Mid Kent Conservative Association.

Also signing the letter were Cllr Gary Etheridge, chairman of Rochester and Strood Conservative Association, Sevenoaks Conservative Association chairman Paulette Furse, Aylesford Conservative Association chairman Andrew Kennedy, Gravesham Conservative Association chairman Cllr Diane Marsh and Rebecca Ryan of the Kent Area Management Board Executive.

The timing of the letter as the party’s conference gets underway underlines the challenge facing the Prime Minister as she strives to build a consensus over the terms of the UK’s departure from the EU.

Paul Cooper said there was dismay over the way negotiations were being conducted.

“We seem to have come up with a solution that doesn’t satisfy either those in the remain camp and those who want to leave.”

The government had forfeited the advantage it might have had by pressing for a ‘Canada deal’ at the outset.

“It [the letter] may not be helpful to the leadership but personally, I am finding that among the party, people feel the Chequers deal is not fit for purpose.”