The Red C poll in tomorrow's Sunday Business Post shows an even bigger Yes lead among those who say they are most likely to vote.
Red C surveyed more than 1,000 voters around the country on Monday, Tuesday and Wednesday for the poll.
The results show support for Lisbon holding up, with 52% of adults saying they will vote for the Treaty, 25% saying they will vote against and 23% are undecided.
When the don't knows are excluded, the Yes side leads by 67% to 33 - a two to one margin.
Red C also asked people whether they are likely to vote, and among those most likely to go to the polls on 2 October, the Yes side is even further ahead, by 73% 27%, once the undecideds are excluded.
The Yes side's two to one lead among all voters is a much stronger position than in the first Lisbon Referendum campaign when with three weeks to go then, Red C showed the two sides much closer, with the Yes side ahead by just 56% to 43%.
