Hanson-Young not afraid of losing seat

South Australian Greens Senator Sarah-Hanson Young has played down the prospect of losing her seat to newcomer Robert Simms in an early poll.

The Greens are thought to be at risk of losing a senate seat in SA in a double dissolution election, adding extra weight to an internal preselection contest.

"The Greens will fight tooth and nail to ensure we have strong representation ... and we know we've got more support than ever before," Senator Hanson-Young told reporters in Adelaide on Wednesday.