Housing minister Stuart Andrew has become the latest minister to resign from the government.
More than 15 government ministers and officials have resigned so far today following the high-profile exits of Rishi Sunak and Sajid Javid last night.
It comes amid disquiet over Prime Minister Boris Johnson's handling of the appointment of former housing minister Christopher Pincher as deputy chief whip.
Andrew said in a letter this afternoon: "Loyalty and unity are traits that I have always endeavoured to provide for our great party.
"However, I fear I have let these override my judgement recently.
"There comes a time when you have to look at your own personal integrity and that time is now."
He also apologised to the sector which will "have to get to know yet another housing minister."
Andrew was the 11th housing minister in 10 years and served for just 148 days.
He said in a tweet accompanying the letter: "It is with sadness that I am resigning as Housing Minister.
"I pay tribute to all my ministerial colleagues, officials, and civil servants in the department and the wider sector. I look forward to continuing to serve my constituents in Pudsey, Horsforth, and Aireborough."
Housing Secretary Michael Gove is understood to be remaining in post but was not at Prime Minister's Questions today.