"It's still not clear how many votes are to be counted," he said yesterday.

"While the margin has improved significantly and it's highly likely the result will be a sixth term, it's not all over as yet.

"Many unusual things have occurred," he said - a reference to 200 votes being discovered in the wrong party's pile earlier in the count.

"I'm almost certain the result will be a positive one but until the returning officer declares the result, I am always keen not to get ahead of myself."

While Mr Billson said he had been encouraged by postal vote returns, Labor had received a good share of absentee votes.

Dunkley was considered nominally marginal as it required a 4per cent swing to change hands.

But a 3.05per cent swing so far against the well-regarded MP means the seat would be lost in the next election with a swing of under 1per cent.

As of Monday afternoon, Mr Billson was 1559 votes in front of Ms Constas on a two-party preferred basis.

Greens candidate Simon Tiller, whose preferences buoyed Ms Constas's vote, was third with a primary vote of 8975, representing a 3.6per cent lift in support for the Greens from the previous poll.

Mr Tiller was delighted with the Greens performance.

"To everyone who voted Greens in Dunkley, your vote has made a real difference, delivering around a 50per cent increase for Dunkley Greens to over 11per cent of first preference votes," the Seaford architect said.

"I saw and heard so many great stories and positive reactions from voters throughout election day. From biological scientists to construction workers and first-time voters to seniors we found agreement and smiles," he said, before thanking hard-working volunteers.

Sandra Bull