Elizabeth May has to go, and I feel horrible saying it.

By most measures, May is a remarkable politician. She is trained in both law and theology and has written eight books. As the executive director of the Sierra Club of Canada, she was awarded an Order of Canada for her leadership in the environmental movement, and that was even before she became the Green party’s first member of Parliament.

In Ottawa, May has been far more noticeable than most MPs. She was responsible for the passage of at least one bill, and has been a consistently constructive voice of the opposition. Her critiques of the outgoing Conservative government were typically sensible, in contrast to the often melodramatic hysterics from the Liberal and NDP benches. And she led the charge against Bill C-51, the Anti-Terrorism Act. Nonetheless, May should resign. And, again, I feel terrible pointing this out.

May is one of the most congenial figures in Canadian politics. She is well-liked by members of all political parties. In fact, MPs voted her “Parliamentarian of the Year,” “Hardest-working MP” and “Best orator” at this magazine’s annual award galas. But still, May should quit politics.

When she took over the Green party in 2006, it was nothing more than a fringe political association. The party had held neither office nor the attention of the public. She began to change this. By the 2008 federal election, almost a million Canadians voted for the Greens, a 40 per cent increase over their 2006 numbers. But, three years later, even though May herself was elected to Parliament, Green support plummeted back to its pre-May numbers, and that’s where it has stayed.

In 2006, under their former leader Jim Harris, the Green party attracted 664,000 votes. In 2015, after nine years of May’s leadership, this has shrunk to 606,000. As a proportion of the popular vote, this is a drop from 4.5 per cent to 3.5 per cent, the party’s worse showing in more than a decade.

It is not all bad news. May has tripled donations to her party, surpassing $3 million in contributions last year. Unfortunately, regardless of how much more money was raised, it did not translate into votes.

Worse, May has done an equally poor job as the most prominent leader in Canada’s environmental movement. In that capacity, she has been omnipresent for the past nine years, making speeches, giving interviews, writing books, all to promote the Green party and the issue of climate change. The result? The public has actually become less interested in both the issue and her party.

Last month, The Environics Institute released a public opinion study on climate change. It found that Canadians have become significantly less concerned about the issue since May took over the Green party. In 2007, 67 per cent of the public was either “concerned” or “extremely concerned” about climate change. This number has declined every year since, and is now reduced to only 50 per cent of Canadians. Meanwhile, scientists at the National Centers for Environmental Information in the U.S. just revealed that 2015 was the hottest summer in 4,000 years. And yet, Environics reports that the number of Canadians who are “not at all concerned” has doubled in the last decade.

It would seem unfair to blame Canadians’ stunning indifference on May. Correlation is not causation. But, at the very least, as Canada’s most prominent environmental advocate, Elizabeth May has been unable to reverse these trends. While her party has languished, so, too, has the movement it is meant to champion.

And perhaps it’s not entirely May’s fault that Green party support has leached away during her term as leader. Party spokesman Julian Morelli pointed out to me that, in 2008, when May was permitted to participate in the widely televised consortium debates, support spiked. This year, as support collapsed, she was only able to join two of the five debates. But even if the party is the victim of circumstances beyond its control, at the very least, we must acknowledge that its leader was unable to overcome this handicap.

May is a remarkable person. She has done great things. Everyone who meets her likes her. But charm and a good CV is not what the Green party needs in a leader. It needs someone who can take the movement to a new level; someone who can effectively compel the Liberals (who have a very poor track record on this file) to honour and exceed their climate change promises. It needs someone formidable, who can succeed in spite of the unfair political landscape.

May has spent nine years trying to be that leader, and has failed. No matter how obvious this is, I still feel terrible having to say it out loud: It is time for her to go.

Scott Gilmore is a Conservative appointee to the board of the International Development Research Centre and he’s married to a newly elected Liberal MP. His full disclosures can be read on his LinkedIn page.