Richard Di Natale is confident that he can increase the Greens party vote, but it will not be done over one or two electoral cycles.

New Greens leader Richard Di Natale believes he can double his party's vote to 20 per cent nationally but cautions it could take at least a decade.

Senator Di Natale, who took over as leader on May 6 after Christine Milne stepped down, told The Australian Financial Review the Greens could broaden their appeal without fracturing as happened to the Australian Democrats after they cut a GST deal with John Howard.

"Over the long term I can't see any reason why we can't get to 20 per cent but I'm not silly enough to think it's going to happen over one or two electoral cycles."

Greens Leader Senator Richard Di Natale says the party has core values, such as same-sex marriage and climate change, that have become more mainstream. Andrew Meares

"I think if you look a decade or so into the future, there is no reason we can't be achieving that mark."

Last decade, the Australian Democrats went from being the third largest federal political party to vanishing after they moved into the mainstream by brokering the GST deal.