The polling is becoming increasingly definitive in the race to become the next prime minister.
The latest, on Wednesday night, is a Conservative Home survey that has Truss on 58% while Sunak is down on 26%.
Although 12% are undecided - that is still too big a climb for the former chancellor. Con Home is based on a self-selecting panel.
But YouGov's latest poll has the foreign secretary at 69% while the former chancellor is down on 31%. Truss has a huge 38 point lead - even bigger than the 24 point lead she had in July.
For Chris Curtis, head of political polling at Opinium, it's a very clear cut outcome.
"Conservative Party members polling is notoriously difficult," he admitted - saying there weren't that many members and so the results can be somewhat inaccurate.
Chris Curtis, head of political polling at Opinium, breaks down what the latest polls mean
But he added: "Despite that fact, the current lead that we are seeing for Liz Truss is so large that even if there were to be a polling error we are fairly confident she is going to win."
He said that delayed ballots because of security worries would give Sunak a little more time - but not enough to close the gap.
Asked why he would be so far behind, Curtis added: "I think one of the biggest problems Rishi Sunak has is that he ended up being the person who brought down Boris Johnson and that means that a lot of Conservative members - particularly those who didn't think it was time for Boris Johnson to go - just don't trust him anymore."
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