Abbott likely to face daunting assortment of senators

Former Labor Prime Minister Paul Keating called Australia's senators "unrepresentative swill".

Opposition leader Tony Abbott might feel the same if he wins power today.

With the Greens, independents and a mass of minor parties loading the 529 candidates seeking the 40 Senate seats available in this election, Abbott has almost certainly no hope of winning control.

He has frantically targeted the Greens, who hold the balance of power, urging Liberals to vote Labor ahead of Green candidates, and has been warning against voting for other minnows for fear of electing "another circus".

The outcome in the Upper House is all but impossible to predict. Polls show support for the Greens has been slipping, with at least one of their senators, South Australian Sarah Hanson-Young, likely to lose.

The profusion of preference swamps between other small parties, mostly right-wing, could produce a hat-load of surprises.

One Nation's Pauline Hanson, and candidates from millionaire Clive Palmer's United Party, Queensland maverick Bob Katter's Australian Party, Family First and the Shooters' and Fishers' Party are considered potential winners.

The nightmare for Abbott is the potential for a wilful Senate to block key policies.

Labor and the Greens have pledged to frustrate his plans to end carbon emissions trading and a swag of other initiatives, leaving Abbott with the choice of caving in or taking the nation to a new election. He has already indicated he is prepared to go back to the ballot box if he cannot push his policies into law.