In the biggest vote for a third party since the Second World War, The Greens will return to federal parliament with eight and possibly nine senators and the House of Representatives seat of Melbourne, Australian Greens Deputy Leader Christine Milne said today.

"We have achieved balance of power in the Senate and will use that power responsibly for good and progressive outcomes for the people of Australia.

"Regardless of which party forms government, we will work with them using the huge experience we have with balance of power politics.

Australian Greens Senators, Bob Brown and Christine Milne are delighted to announce Dr Geoff Couser as the Greens federal candidate for Denison.

Dr Couser comes to the Greens as a staff emergency specialist at the Royal Hobart Hospital and a passionate spokesperson for Tasmania's unique environment.

"Geoff Couser will be a great and true representative for the people of Denison," says Senator Brown.

"Dr Couser will be a strong performer in parliament. He will bring a fair, balanced and sensible voice to a lower house that is dominated by the two old parties,"

Australian Greens Deputy Leader, Christine Milne has introduced candidates for the Greens' Tasmanian Senate ticket.

Senator Milne will be the lead candidate, followed by Tamar Valley economist and business owner, Peter Whish-Wilson, and Hobart tourist operator Penelope Ann.

The official announcement took place today at Launceston City Park, where Senator Milne was joined by her two running mates.