The Green Party's only MP Caroline Lucas has indicated she would be willing to make an electoral pact with Labour.
Lucas, MP for Brighton Pavilion, said she would consider a deal with other parties, including Labour, with candidates agreeing not to compete in some constituencies.
By reaching a deal for a so-called "progressive alliance" both parties' could, in theory, allocate resources more effectively at election time, and possibly win more seats.
However, Lucas said it will ultimately be for the party to decide on such a policy.
The news comes as voting closes in the Green Party leadership election, with Lucas the overwhelming favourite to win the contest.
She said: "It doesn't make sense for parties of the left to be constantly fighting each other and meanwhile the Conservatives come through and we've seen that time after time in the 2015 general election.
"I think what we are looking at is those marginal constituencies where some kind of agreement between progressive parties might be able to make a difference."
Lucas added that she would even be willing to stand aside herself.