The third member of Boris Johnson's cabinet to quit this week was Simon Hart, a member of the British parliament who served as Secretary of State for Wales.
Hart said in his letter that he felt there was no other option left to change.
His resignation comes a day after Sajid Javid handed in his resignation.
In their resignation letters, none of the three cabinet members cited any specific incident that caused them to lose confidence in Johnson, but the moves come amid allegations the prime minister lied to officials when he said he was unaware of sexual harassment allegations against a former deputy chief whip.
The Levelling Up Secretary was fired by Johnson after Gove told him to step down.
On Wednesday, dozens of junior ministers and secretaries resigned.
"Colleagues have done their upmost in private and public to help you turn the ship around, but it is with sadness that I feel we have reached the point where this is possible," Hart wrote.
According to Britain's Press Association, Johnson said Wednesday that he would stay to address important issues.
After months of mounting criticism of the prime minister for a series of scandals, calls for his resignation are reaching a climax. In April of this year, Johnson became the first sitting prime minister to be punished for a crime when he paid a fine for illegally holding parties at Downing Street. Conservative party members called for a no confidence vote in Johnson, but he survived the vote with the support of his caucus.
The U.K. prime minister survived a confidence vote.
Boris Johnson is fighting for survival after a wave of government resignations.
Britain's Boris Johnson is fighting to stay as Prime Minister.
Michael Gove was fired after he urged the Prime Minister to resign.