Election 2015: Greens could be decisive, Natalie Bennett says
The Green Party could be in a "very decisive place" in a hung parliament after the general election, its leader in England and Wales has predicted.
Natalie Bennett said a membership surge made hers the "third biggest party in England" after the Tories and Labour.
The Greens are looking to add to the one MP they gained in Brighton Pavilion five years ago.
Speaking as the campaign officially got under way, Ms Bennett said voters were "desperate for change".
She told BBC News people were "fed up" with the current first-past-the-post electoral system, seen as a disadvantage to smaller parties.
"We've got the kind of politics we have now through people, through generations, voting tactically," she said.
"And that's let the biggest parties focus on the swing voters in the swing seats.
"If we want a different sort of politics, it's in the voters' hands."
The Greens have been polling in similar numbers to the Lib Dems and say their membership quadrupled in the past year.
With polls suggesting a hung parliament could be likely after the general election, the party has previously floated the idea of a "progressive alliance" also involving the SNP.
Ms Bennett said the Greens would "not in any way" support a Conservative minority government, but would consider a "vote by vote" arrangement with Labour.
The Green Party in England and Wales is fielding its largest ever slate of candidates, aiming to stand in 90% of parliamentary seats on 7 May. The Green parties in Scotland and Northern Ireland are separate organisations.
Ms Bennett also said her party would offer a "message of hope" and that people were "sick of business-as-usual politics".
Her party's policies include building 500,000 social rented homes, a new "wealth tax" on the richest 1%, and increasing the minimum wage to £10 an hour by 2020.