The Sydney electorate of Warringah will be one of the most fascinating battlegrounds in the May election, with a high profile independent Zali Stegall challenging former prime minister Tony Abbott.

Despite the seat being on about 11 per cent, Abbott describes this as a “full on marginal seat campaign”.

Abbott is running hard on local issues. He says over-development and traffic congestion are the biggest issues and if reelected he is keen to use his position to be a “champion” for the Northern beaches tunnel. He’s trying to tone down his stridency, this week attempting to avoid being drawn to deeply into the row around the criminal conviction of Cardinal George Pell.

Steggall, a lawyer and former Olympian, is running against Abbott on a campaign that says Warringah voters want “a new voice”.

Keenly focused on climate change policy, Steggall is very critical of the government’s efforts and says even Labor’s energy policy “needs again to be toughened up.”

Steggall, who grew up and lives in the electorate, has only had Abbott as an MP and has never voted Liberal nor has she had voted Labor.

Pressed on who she had voted for, she told The Conversation she has mostly voted independent but “wouldn’t want to say never” to having voted Greens.