Sunak, late Friday became the first Tory leadership contender to reach the 100-nomination threshold in the race for the top post in UK govt.
Truss had been forced to abandon almost all her policy programme after it triggered a bond market rout during her 6 weeks stint as the PM.
The leadership contest began in July after Johnson announced his resignation following a slew of scandals and resignations from his government.
Rishi Sunak launched repeated attacks on the economic policies of the favorite Liz Truss in their first head-to-head TV debate.