The Greens' most venerated elder statesman has targeted the lower house seat of Brisbane as "inevitably Green", but Bob Brown conceded it could take an election or two.

Former Greens leader Mr Brown and his successor, Christine Milne, were campaigning in Brisbane on Tuesday to boost the party's chances of picking up a second Queensland Senate seat.

Bob Brown, Senator Larissa Waters, Christine Milne and candidate Andrew Bartlett pressed the flesh at a Brisbane pre-poll on Tuesday. Credit:Robert Shakespeare

But Dr Brown, who was basking in poll results that showed a possible win in the Melbourne seat of Batman, said the Greens also had eyes on a lower house Queensland seat in the long term.

"Brisbane is inevitably going to become a Green seat in the Federal Parliament, if not this time then further down the line," he said.