Ms Truss will now return to the back benches and has insisted she stay on as an MP for the constituency in its location is in southwest Norfolk.
She will be one of three former prime ministers in House of Commons, along with Boris Johnson and Theresa May – first time that has happened since 1983.
Allies said she would continue to make her case in service of tax cuts from green benches behind Mr Sunak.
Labor tore apart Ms. Truss over her farewell speech, which stated that she had no remorse for economic chaos caused on her mini budget.
Anneliese Dodds, shadow equality secretary, said voters would be “very upset” that the outgoing prime minister did not take responsibility.
“Rishi Sunak cannot be the answer when problem is the Conservative Party.m We need have general choices to deliver fresh start that our country is crying out for,” she said.
Daisy Cooper, Deputy Leader of liberal democrats, added:” past 50 days of The conservative chaos has done irreparable damage to our country.”
