A leading environmental advocacy group is endorsing former Vice President Joe Biden for president, saying that November’s presidential election “is our last, best chance to address the climate crisis.”

The political wing of the League of Conservation Voters stressed on Monday as it backed the presumptive Democratic presidential nominee that the nation “cannot afford the cost of inaction or another four years of a Trump presidency.”

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“Donald Trump is the most anti-environmental president in history, period,” argued Tiernan Sittenfeld, League of Conservation Voters Action Fund senior vice president. “Voters are demanding action and we are confident that, as president, Biden will immediately put our country on track for a 100 percent clean energy economy with policies centered in justice and equity that restore America’s global climate leadership.”

The group – which works to elect pro-environmental candidates – shelled out a record $60 million to support pro-environmental candidates in the 2018 midterm elections.

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Biden, in a statement, emphasized that climate change “is an existential threat, and there is no greater challenge and opportunity facing our country and our world.”

“For me, this is personal: I live in a state that's dealing firsthand with the impacts of climate change and impacts of pollution on kids and families. I'm going to fight for my grandkids, for the families rocked by super storms and environmental injustice, and the upside — those good-paying jobs that will power a green economy,” the former vice president added.

Climate change was one of the leading issues in the Democratic presidential primaries, particularly among younger and more progressive voters who supported Sen. Bernie Sanders of Vermont -- voters Biden is now trying to court as he moves to unify the Democratic Party.

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Biden touted that he introduced “a bold plan to lead a clean energy revolution and fight for environmental justice" during the primaries. And making some news, Biden said he’s working on expanding his proposal in the coming months.

"To achieve this aim, I have asked my campaign to commence a process to meaningfully engage with more voices from the climate movement — including environmental justice leaders and worker organizations, and collaborate on additional policies in areas ranging from environmental justice to new, concrete goals we can achieve within a decade, to more investments in a clean energy economy,” Biden explained.

The LCV’s endorsement of Biden comes two days before the 50th anniversary of Earth Day, which is celebrated each year to demonstrate support for environmental protection.