Red Wall Tory MP Aaron Bell has become the latest to confirm he has submitted a letter of no confidence in Boris Johnson.
In a statement, the Newcastle-under-Lyme MP blamed the partygate scandal had left him with no choice.
Bell said he was “profoundly disappointed it has come to this”.
His intervention comes as Downing Street was forced to deny that Johnson had “lost control” following the departures of five No. 10 aides in the last 24 hours.
He is the 11th Conservative MP to confirm that they have submitted no confidence letters to Sir Graham Brady, chair of the 1922 committee of Tory backbenchers.
It is thought that the total number of letters that have gone in could be in the 40s. A total of 54 are needed to trigger a no confidence vote.
Bell, who was elected in 2019, confirmed he had submitted his letter on January 12 after a session of prime minister’s questions.
“As someone who backed Brexit and backed Boris Johnson for the leadership in 2019, I am profoundly disappointed it has come to this,” he wrote.
“The government that the prime minister has led has delivered some huge successes, including the vaccine rollout and nearly £35m for Newcastle under Lyme to level up.
“However, the breach of trust that the events in No.10 Downing Street represent, and the manner in which they have been handled, makes his position untenable.”
Bell made his feelings known towards the prime minister in a debate in parliament following the release of a report into Downing Street parties by Whitehall mandarin Sue Gray.
The partial report blamed the parties in No.10 on “failures of leadership and judgment”.
Bell recounted how he attended his grandmother’s funeral in May 2020 and, due to rules in place at the time, did not hug family members and then drove straight to Staffordshire.
“Does the prime minister think I’m a fool?” he asked.