Democrat frontrunner Joe Biden told supporters in Iowa on Tuesday he supports having a primary debate focused solely on climate change.

The topic came up during Biden’s brief discussion with a Greenpeace activist. Biden said he is “all in.”

“That’s what we should be doing,” Biden said, according to the Washington Post. “I’m all in, man. Take a look at what I’m talking about – and by the way, the first climate change plan in the history of the Congress? Biden.”

A number of Democrat candidates are making climate change cornerstones of their campaigns. In early June, Biden released his plan to combat climate change, calling the Green New Deal “crucial framework.”

The proposal read in part:

Biden believes the Green New Deal is a crucial framework for meeting the climate challenges we face. It powerfully captures two basic truths, which are at the core of his plan: (1) the United States urgently needs to embrace greater ambition on an epic scale to meet the scope of this challenge, and (2) our environment and our economy are completely and totally connected.

Biden’s plan involves spending $1.7 trillion in clean energy investments, achieving a 100 percent “clean energy economy” and reaching a net-zero greenhouse emissions goal by 2050. He plans to pay for this, in part, by reversing President Trump’s successful tax cuts.

The Biden plan will be paid for by reversing the excesses of the Trump tax cuts for corporations, reducing incentives for tax havens, evasion, and outsourcing, ensuring corporations pay their fair share, closing other loopholes in our tax code that reward wealth not work, and ending subsidies for fossil fuels.

As Breitbart News reported: “The plan calls for every new light and medium duty vehicle sold in America to be electric, banning new oil and gas permits on public lands and doubling offshore wind energy production by 2030.”

The effectiveness of Biden’s proposal has been called into question.

“One report from the libertarian Cato Institute found that such a proposal would prevent warming by 0.137 degrees Celsius by 2100,” USA Today reported.

Biden’s plan has been ripped by Green New Deal advocate Alexandria Ocasio-Cortez, who supports Washington Gov. Jay Inslee’s (D) plan, calling it the “gold standard.” It promises 100 percent renewable energy by 2035.

“I do think that Jay Inslee’s plan is a phenomenal blueprint and example of where we need to go. It’s got the scale, the jobs and justice,” Ocasio-Cortez said, according to the Hill.

“Scientifically, anything that is less than helping us cut carbon emissions in half by 2030 is going to be too late,” she added.

Biden is one of many candidates to step up and call for a debate solely on climate change. Sen. Elizabeth Warren (D-MA), Beto O’Rourke (D), Sen. Bernie Sanders (I-VT), and Sen. Kirsten Gillibrand (D-NY) have expressed support for such a debate. The Democratic National Committee, however, has not been receptive to hosting a debate focusing primarily on one issue.

“It’s just not practical,”DNC Chairman Tom Perez told a group in Orlando. “As someone who worked for Barack Obama, the most remarkable thing about him was his tenacity to multitask, and a president must be able to multitask.” Some Democrat candidates– especially Inslee, who practically built his campaign on the single issue of climate change– are calling for the DNC to step up.