Jim Harris says he will not join the race to determine who will take the party into the next federal election.

"It has been an intense time for me over the last few years, and I am announcing today that I will not be seeking the leadership of the Green party again," said Harris on Monday, who has led the party for nearly four years.

Although Harris survived his own party's leadership vote in August 2004, winning 54.8 per cent of votes, he saw a strong challenge from Ontario farmer Tom Manley, who had 36.8 per cent of the vote.

So far, there is only one declared candidate in the Green leadership race.

David Chernushenko, the bilingual deputy leader of the Green Party, announced last month that he would be throwing his hat into the ring.

"Nobody has worked harder than Jim Harris. I want to thank Jim for having played a critical role in the Green Party's vault from the fringes to the heart of Canadian politics," Chernushenko said in a written statement on Monday.

In the last election, Chernushenko got 10 per cent of the vote in the riding of Ottawa Centre, formerly held by NDP stalwart Ed Broadbent.

"Jim believed that the Green Party was capable of running in all 308 ridings and breaking the two per cent barrier that qualified the party for public financing. With Jim leading the charge, we accomplished both, not just once but twice," said Chernushenko.

"Whoever succeeds Jim will have the advantage of leading a stronger and more widely respected party than when Jim was first elected."

Elizabeth May, who resigned as executive director of the Sierra Club of Canada earlier this month, has said she is also seriously considering a leadership bid.

Harris "is happy to see that there is already a strong candidate in the leadership race" and that another is contemplating a campaign, said the source.

The Green party, which holds leadership elections every two years, will stage its national leadership convention in Ottawa in late August.

Despite having access to substantial federal funding for the first time, the party won no seats and achieved only a slight improvement in its share of the popular vote, to 4.5 per cent from 4.3 per cent in 2004.

Still, party officials consider the results to be a success because the Greens increased their number of actual votes by 14.4 per cent over 2004.

The party also surpassed the two-per-cent threshold required to be eligible for federal-election financing of $1.79 a voter.