Victorians today head for the polls in what is expected to be a cliffhanger election as Labor tries to extend its 11 years in power against a resurgent Opposition and soaring Greens.

Polls indicate that Premier John Brumby can at best hope for a narrow victory, or a hung parliament in which the Greens and possibly some independents hold the balance of power.

The Greens also appear likely to win the balance of power in the State's Upper House.

The final outcome, which may not be known for days, could closely mirror August's federal election that saw Prime Minister Julia Gillard cling to office only with the votes of one Greens and three independent MPs, and the balance of power in the Senate shifting to the Greens next July.

In state elections earlier this year Labor scraped home in Tasmania with the help of the Greens, and retained power in South Australia by a hairsbreadth.

Labor Governments in New South Wales and Queensland have yet to face voters in elections that many commentators believe could see them ousted by oppositions riding on a wave of public anger.

Western Australia is the only state in which the Coalition holds office.

In Victoria, neither party has gained a clear advantage from promises totalling more than A$16 billion ($20.5 billion), most matching each other.

Key areas have included education, employment, payroll tax and stamp duty cuts, trains, law and order, energy costs and ambulance services.

The picture has been clouded further by complex preference deals that saw, for example, the Coalition preferencing the Greens in a move that some analysts believe could help Brumby retain power.

Two weeks ago a Nielsen poll in the Age newspaper showed the Opposition narrowing the lead with Labor, although this week commentators still maintained that the swing was not sufficient to elect Coalition Leader Ted Baillieu.

Last week a Morgan poll predicted Labor would hold four key inner-Melbourne seats, but yesterday released a new poll that reported a surprise surge for the Coalition, putting the Opposition ahead of Labor by 51 per cent to 49 per cent in the two-party preferred vote that decides election outcomes.

A Galaxy poll in the Herald Sun yesterday said that for the first time in its polling Labor and the Opposition were running 50-50 in the two-party preferred vote.

But it said Greens preferences were likely to return Labor for a record fourth term.