Boris Johnson is to resign on Thursday as Conservative leader but will push to stay on as prime minister until autumn, prompting a backlash from some Tory MPs who say he has to go now.

Johnson resigned after an extraordinary standoff with his cabinet, which ended after Nadhim Zahawi, his new chancellor, told him to quit. By that point, more than 50 ministers had walked out, citing his mishandling of a string of scandals and failure of ethics.

A No 10 spokesperson said: “The prime minister will make a statement to the country today.”

Johnson is understood to have spoken to the Queen to tell her of his plans. However, his push to stay on as prime minister until the autumn while a Conservative leadership contest takes place provoked fury among MPs.

Kwasi Kwarteng, the business secretary, said the party needed “a new leader as soon as practicable”.

“Someone who can rebuild trust, heal the country, and set out a new, sensible and consistent economic approach to help families,” he added.