The new Greens leader, Victorian Senator Richard Di Natale, faces a significant challenge in the run-up to the next election.

Christine Milne successfully led the Greens out of the giant shadow of Bob Brown when he retired in 2012. Under Milne, the party achieved its highest ever parliamentary representation. Unlike Milne, who was a veteran of Tasmanian politics, a former state party leader and a well-known deputy under Brown, Di Natale has virtually no profile outside Canberra. Nor does he have Milne’s political experience — she supported a minority Liberal government in Tasmania and a minority Labor government nationally, while he has been in the Senate just under four years.

Nonetheless, the point was always going to come for the Greens, with the transition for the party from microparty status dominated by the Tasmanian Greens to a substantial party in its own right, with more senators than the Nationals, and strong representation from right across the country. Di Natale now has the task both of establishing his own political identity and of shoring up the party in states like NSW and Queensland, where the Greens’ continuing hold on Senate spots isn’t guaranteed — while negotiating with a government desperate to secure passage of more of its agenda.

The election — unusually — of co-deputy leaders is an interesting one. Larissa Waters and Scott Ludlam will jointly hold the position, with former deputy Adam Bandt pushed down the pecking order. Ludlam, easily one of the most impressive senators or MPs of any party, is surely a future leader who will benefit from a more senior role within the party.

More so than when Bob Brown retired, the Greens face a crucial moment. Generational change, a key moment in the growth of political parties, has occurred for the first time. Whether the new generation can match the one now departing isn’t yet clear.