As the federal Green Party's leadership race heats up, one candidate is saying he wants the party to take a hard turn to the left.

Alex Tyrrell, leader of Quebec's Green Party, will announce Wednesday morning that he's entering the race to replace Elizabeth May as leader of the federal party.

Days before May's resignation in November, Tyrrell was leading the calls within the party for her to resign. He launched a petition asking for an open leadership race and criticized May for taking the federal Greens too far to the centre.

Tyrrell denounced the party's 2019 slogan ("Not Left. Not Right. Forward Together") and ambiguous messaging on abortion and Bill 21, the law barring Quebec public servants from wearing religious symbols.

Tyrrell said Canada's Greens need to become "eco-socialists" who are committed to protecting the environment while pursuing evergreen left-centre policy goals — such as universal pharmacare and free university tuition — and reforming capitalism to reduce economic inequality.

"Green Party members are looking for a leader who can modernize the party by bringing in a bold, progressive, eco-socialist platform that reflects the scientific consensus on climate change while standing up for social justice," Tyrrell said in a website post, provided to CBC in advance.

Tyrrell, who describes himself as an activist, said he is on "a mission to implement progressive change in this country."

If he's chosen as the next Green leader, Tyrrell said he'll also push to:

Close Alberta's oilsands within the first four years of a Green mandate.

Increase taxation on the wealthy, big businesses and polluters.

Link major cities in Canada by high-speed electric rail.

Generate new revenues and, where necessary, incur deficits to accommodate his green transition and abandon "fiscal conservatism."

Amend the Constitution to guarantee Canadians access to clean air, water, housing and healthy food.

Tyrrell has led the Green Party of Quebec for six years. Although Greens hold seats in legislatures in P.E.I., New Brunswick, Ontario and B.C., the Quebec party has never run a full slate of candidates or elected anyone to Quebec's National Assembly.

Aside from Tyrrell, two other Greens have declared they'll be entering the leadership race: former Quebec Green candidate Julie Tremblay-Cloutier and former Liberal David Merner.

In an interview last week with CBC, Tremblay-Cloutier said she doesn't believe in labels but thinks the Greens should embrace environmental and socialist values.

"People here in Quebec especially, we don't talk about politics much in that way," Tremblay-Cloutier told CBC News last week. "But yes, if being 'left' means being more socialist or eco-socialist, I guess I'm more of a left turn."

Merner, on the other hand, said he believes the party needs to stick to the centre.

"What folks were saying to me early on is we don't want to marginalize ourselves," Merner said. "And if we head down the eco-socialist path, we will not succeed."

The leadership race for the Greens is expected to begin on Feb. 3; the Greens will elect their new leader in Charlottetown, P.E.I. in October.