Once you make that decision on Thursday, there's no going back, he added
According to a recent YouGov poll, 62% of them want Truss for leader, giving her a colossal 24-point advantage over Sunak
The Wigan MP is the fourth contender to officially declare her bid in the race
On June 8, Britain goes to polls in snap election unexpectedly called by Prime Minister Theresa May
The campaign was suspended for several days last month after the Manchester attack
May's lead dipped by six percentage points as voters reacted badly to the Conservatives' manifesto