Sen. Cory Booker (D-N.J.) on Friday became the second likely contender for the Democratic presidential nomination in 2020 to back the Green New Deal, the radical plan to zero out greenhouse gas emissions in a decade and reduce poverty with federally backed clean-energy jobs.

“We must take bold action on climate change & create a green economy that benefits all Americans,” Booker tweeted. “Excited to support a #GreenNewDeal.”

The Green New Deal stormed from the fringes of policy debates into the Democratic mainstream in barely a month as grassroots protesters with the progressive groups Sunrise Movement and Justice Democrats began bird-dogging top party officials, demanding bold action to combat climate change.

Rep.-elect Alexandria Ocasio-Cortez (D-N.Y.) championed the cause, unveiling a resolution to establish a select committee in the House to begin outlining Green New Deal legislation. Weeks later, the proposal has more than three dozen backers in the House and support from nearly half a dozen senators. More than 300 local and state officials on Friday signed an open letter offering support for a Green New Deal.

“It’s going and it’s growing,” Corbin Trent, a spokesman for Ocasio-Cortez, said by phone Friday after Booker’s announcement. “We’ve got some momentum behind something that’s hopefully going to be transformational to our economy and our climate.”

Sen. Bernie Sanders (I-Vt.), another likely candidate in 2020, has also said he supports the plan. Richard Ojeda, the failed West Virginia congressional candidate who declared his candidacy last month, suggested on Twitter he backs the Green New Deal, but a spokesman did not immediately respond to a request for comment. Sen. Jeff Merkley (D-Ore.), a potential 2020 contender, was among the first in the Senate to endorse the effort.

The proposal breaks the boundaries of the last three decades of debate over climate change, shifting from policies focused on the need to tweak markets by putting a price on carbon emissions to large-scale federal intervention the likes of which the United States hasn’t pursued in decades.

Justin Sullivan via Getty Images A search and rescue crew member searches for human remains at a mobile home park that was destroyed by the Camp Fire in California last month.

Climate change went largely ignored during the 2016 presidential election. In the years since, the crisis of human-caused global warming became disturbingly tangible as record-breaking storms and wildfires killed thousands and destroyed property worth hundreds of billions of dollars. In an ironic twist, President Donald Trump’s bellicose denial of the scientific realities of human-caused global warming, rollbacks of greenhouse gas regulations and decision to withdraw from the Paris climate accords helped propel the issue into mainstream political discourse.

It’s still unclear what a Green New Deal would entail, but the key point is to eliminate net emissions by 2030. That’s the deadline by which world governments must halve global emissions to keep the planet from warming by 2.3 degrees Fahrenheit, scientists at the United Nations’ Intergovernmental Panel on Climate Change determined in October. Climate change is forecast to be cataclysmic beyond that temperature.

The other core pillar is using the rapid build up of renewable and energy-efficiency infrastructure to reduce unemployment and under-employment, and provide funding to transition workers in fossil fuel industries into new jobs and aid communities sickened and impoverished by the oil, gas and coal pollution.

In April, Booker announced legislation to lay the groundwork for a federal jobs guarantee ― a policy first proposed in the 1930s under the original New Deal. On Friday, he indicated that such a policy would serve as a vehicle for a Green New Deal.

It’s clear that any politician who wants to be taken seriously by our generation needs to have the courage to stand up to the fossil fuel billionaires and back a Green New Deal. Varshini Prakash, co-founder of Sunrise Movement

Booker’s record on environmental issues is strong. As the mayor of Newark, New Jersey, he established the city’s first environmental commission and Office of Sustainability and contracted energy-efficiency retrofits on city buildings to a union that specializes in green construction. In the Senate, Booker pushed to extend tax credits on renewable energy, fought offshore drilling and seismic testing and was one of only 10 senators to attend the Paris climate talks in 2015. In October 2017, he introduced a bill to require federal agencies to address environmental justice issues in low-income and ethnically marginalized communities.

The nonpartisan League of Conservation Voters scored him at 100 percent last year and 98 percent over his lifetime on its ranking, which is based on how lawmakers vote.

Booker has been criticized for accepting donations from major corporate players, including the pharmaceutical giants based in his state and the finance, insurance and real estate industries that make up the bulk of his campaign fundraising. But, according to data collected by the nonpartisan Center for Responsive Politics, the energy and natural resources industries contributed about $331,000 to him between 2013 and 2018, less than half of which came from corporate political action committees.

“Cory Booker taking this step is huge for our movement and huge for the Democratic Party,” said Waleed Shahid, the communications director for Justice Democrats, a left-wing group that helped lead Ocasio-Cortez’s winning primary campaign. He said the group would “hold everyone accountable to not just campaign on the Green New Deal but actually deliver.”

“It’s clear that any politician who wants to be taken seriously by our generation needs to have the courage to stand up to the fossil fuel billionaires and back a Green New Deal,” Varshini Prakash, the co-founder of Sunrise Movement, said in a statement.

The announcement comes as global climate talks are winding down in Katowice, Poland, where the Trump administration drew scorn for promoting fossil fuels and allying with petro-states like Saudi Arabia and Russia weaken support for key scientific findings.