Over 50 members of parliament have resigned from the U.K. Prime Minister Boris Johnson’s government since Tuesday, as the unprecedented revolt against the leader from within his own party continues.

After a torrent of resignations Wednesday, more ministers quit early on Thursday morning, including Northern Ireland Secretary Brandon Lewis, Treasury Minister Helen Whately and Security Minister Damian Hinds.

A Sky News tally puts the total number of departures at 57 as of 9.10 a.m. London time.

Sterling hit a day’s high after multiple news outlets reported mid-morning Thursday that Johnson was set to resign. CNBC and NBC News were unable to independently verify these reports.

The 50th resignation came from George Freeman, a junior minister for science, research and innovation, at around 7.20 a.m. London time. Pensions minister Guy Opperman resigned shortly after.

In a scathing resignation letter to the prime minister, Freeman said the “culmination of your lack of transparency and candour with Parliament (and willingness to ask your Ministers to mislead Parliament), your removal of key pillars of the Ministerial code,

your handling of your appointment of a Deputy Chief Whip who it turns out you knew had a history of sexual abuse allegations, is too much.”

“This is seriously damaging public trust and respect for government, democracy and the law, and this great Party’s long tradition as the party of standards, character, conduct, integrity and duty to office and country before partisan self-interest,” he added.

Johnson met with remaining members of his cabinet on Wednesday night, many of whom were reported to have urged him to step down. 

Downing Street declined to comment when contacted by CNBC. The prime minister has thus far refused calls to resign, vowing to “fight on.”

Chancellor Nadhim Zahawi, appointed on Tuesday following the resignation of Rishi Sunak, also publicly called on the prime minister to step down on Thursday morning, revealing that he and other cabinet ministers told Johnson he should “leave with dignity.”

“I am heartbroken that he hasn’t listened and that he is now undermining the incredible achievements of this Government at this late hour,” Zahawi said in a public letter Thursday morning.

“But the country deserves a Government that is not only stable, but which acts with integrity. Prime minister, you know in your heart what the right thing to do is, and go now.”

New Education Secretary Michelle Donelan, who was appointed to replace the promoted Zahawi on Tuesday, then became the 54th resignation.