Green Party leader Natalie Bennett has suggested she would be "happy" to work with Ukip to push for electoral reform.
The Greens received 1.1 million votes at the general election, while Ukip finished with almost four million - but both parties ended up with just one MP each.
After the results came in, Ms Bennett and Ukip leader Nigel Farage - who both failed to win a seat - spoke of their frustration at the first-past-the-post system.
Asked if the Greens would stand alongside Ukip on a platform for electoral reform, Ms Bennett said: "Lots of people who were in seats where they have never thought about electoral reform before are looking at their MP or local council and are saying 'How did we end up with that? That's not what we wanted'.
"So I think we will see a grassroots campaign and we will be supporting that and very happy to join with anyone else who supports that, working on an issue by issue basis as the Green Party has always done."
Despite finishing third in Holborn and St Pancras at the election, Ms Bennett has said she has no intention to quit as leader.
Today she refused to rule out running at a by-election during this Parliament but described not being an MP as a blessing.
She said: "Obviously I would love the chance to be in Parliament but the reality is that it works very well with Caroline Lucas (the Green Party's only MP) in there fighting almost like the equivalent of the 25 MPs we should have under proportional representation.
"While I'm not an MP what I'm free to do is travel round the country and be very much not Westminster-focused.
"One day I might be in Carlisle, the next day in St Ives and the day after that in Gateshead, and that means I can be the leader of the whole Green Party of England and Wales."
Commenting on the recent appointments to the Tory government's cabinet, Ms Bennett said she was pleased that new Energy Secretary Amber Rudd does not deny climate change.
She said: "One always has to look back to the last Parliament and think 'At least she isn't (former energy secretary) Owen Paterson, who it emerged after he was sacked was a climate change denier.
"What I am concerned about is how much influence she (Ms Rudd) will have in a Government that has shown no commitment during the election campaign to dealing with climate change."
The Green leader also described as "disturbing" the appointment of C aroline Dinenage - who voted against legislation introducing same-sex marriage - as equalities minister.
And she said that she was "gravely concerned" about the Government's move to curb the trade unions' ability to call strikes which affect public services.