Labor leader Michael Daley has struggled to explain the details of his signature election policies in a televised debate as voters prepare to go to the polls in three days.

Mr Daley was debating Premier Gladys Berejiklian before a live audience of 100 undecided voters in Penrith when he failed to recall the costs of his TAFE policy or his Gonski education package – two centrepieces of Labor's election.

Premier Gladys Berejiklian arrives at the leader's debate on Wednesday night. Credit:Wolter Peeters

Ms Berejiklian however stumbled over a question involving Sydney's M4, and whether motorists would be slugged with a new toll between Penrith and Parramatta.

The Premier indicated there would be a toll before later tweeting that there wouldn't be.