Simms, who announced the pre-selection bid on social media this morning, told InDaily “refreshing the Senate ticket” would give the Greens a chance to start “a new conversation with South Australian voters”, focused on economic inequality.

The party elected Simms to fill the casual vacancy created by the retirement of Greens Senator Penny Wright in late 2015, but Hanson-Young’s pre-selection as the party’s number one Senate candidate at the federal election the following year – with Simms placed second – cruelled his chances of retaining the seat.

Insisting he was making no criticism of Hanson-Young or any other potential pre-selection candidate, Simms told InDaily this morning: “We do need to make some changes.”

“What I’d really look to do is have a really big focus on economic inequality … the Greens are the only party that has an alternative to the economic status quo,” he said.

“The widening gap between the mega-rich and everyone else is the key social (issue for) Australia.

“There is the potential to increase our vote and get more traction – and I think I’m someone who’s able to do that.”

He said Hanson-Young was “someone I respect as a colleague” and his nomination was “not about being critical of anyone else”.

Simms nominated “green jobs”, “the future of work”, free university education, public ownership of assets and social housing among the issues he would prosecute if his bid is successful.

Nomination for pre-selection, which is decided by a ballot of rank-and-file Greens members, closes at the end of this week.

“It’s an open process and we have got lots of great people in the Greens,” he said.

“I certainly encourage them to put themselves forward in the spirit of grassroots democracy.

“In other political parties, it’s a faceless man, or the factional warlord (who chooses candidates).”

Hanson-Young told InDaily in a statement that it was “terrific that we have passionate Greens members who are keen to put their hand up and participate in our democratic processes”.

“I feel privileged that as a woman and a mum, the SA Greens have backed me to stand strong for the rights of our children and future generations to a clean and safe environment, where equality and respect for each other and our planet underlines our values and actions.

“Pre-selection contests are the way that members ensure their senators aren’t just working hard, but working hard on the issues that matter to them to ensure we remain the home for progressive voters in South Australia.”

She added that Greens members “know I stand up for our state, our environment and our community.”

Simms was most recently the Greens’ candidate for the state seat of Adelaide, which was retained at this month’s election by Liberal MP Rachel Sanderson.

He received a slight uptick in the Greens vote, up 0.7 per cent to 12.6 per cent, this year compared with the previous state election, at which he was also a candidate for Adelaide.