Democratic presidential hopefuls are battling to be seen as the climate change candidate.

Four 2020 White House contenders already have offered detailed policy plans on how they'd tackle the issue of global warming, a sign the environment has become a top issue in the Democratic primary.

In the past week, Washington Gov. Jay Inslee Jay Robert InsleeBarr asked prosecutors to explore charging Seattle mayor over protest zone: report Bottom line Oregon senator says Trump's blame on 'forest management' for wildfires is 'just a big and devastating lie' MORE (D) and former Texas Rep. Beto O'Rourke Beto O'RourkeJimmy Carter says his son smoked pot with Willie Nelson on White House roof O'Rourke endorses Kennedy for Senate: 'A champion for the values we're most proud of' 2020 Democrats do convention Zoom call MORE (D) each released proposals to curb greenhouse gas emissions. Last month, Sens. Elizabeth Warren Elizabeth WarrenDimon: Wealth tax 'almost impossible to do' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context Democrats shoot down talk of expanding Supreme Court MORE (D-Mass) and Cory Booker Cory Anthony BookerBipartisan praise pours in after Ginsburg's death DHS opens probe into allegations at Georgia ICE facility Democratic lawmakers call for an investigation into allegations of medical neglect at Georgia ICE facility MORE (D-N.J.) introduced, respectively, a public lands and environmental justice proposal, with each addressing curbing emissions.

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The plans allow the candidates to pit themselves directly against the Trump administration, which has moved to pull the U.S. from the landmark Paris climate agreement and has rolled back a number of environmental regulations that affect air pollution.

The proposals could help the candidates get an edge on the competition in the crowded primary. A CNN poll released Tuesday found that combating climate change is the No. 1 issue of concern for Democratic voters, beating out health care, gun control and action on college admissions.

“The greatest threat we face — which will test our country, our democracy, every single one of us — is climate change,” O’Rourke said in a statement when rolling out his plan.

“The Trump administration has gutted the [Environmental Protection Agency], rolled back clean air and clean water protections, and allowed polluters to go unchecked, causing immense harm and suffering by vulnerable communities," Booker said when announcing his.

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Environmental groups see the rollout of the various climate proposals as proof that Democratic contenders are both taking global warming seriously — and realizing voters do, too.

“I think we’re seeing these proposals coming because it’s clear that Americans want leaders who will stand up to the fossil fuel industry that created this climate crisis,” said Charlie Jiang, a climate campaigner for Greenpeace.

“I think all the candidates we’re seeing in the field recognize that climate action and climate justice are top of mind for Americans in 2020.”

May Boeve, executive director of 350 Action, said the growing support for climate action also means candidates are no longer distinguishing themselves by simply believing in climate change, but by developing policies to fix it.

“Voters are making clear that climate change is a top priority issue in this presidential election, and we will support the boldest vision to transform our economy, and stop climate-wrecking fossil fuel projects,” Boeve said in a statement.

“We look forward to seeing the candidates debate their climate plans, strengthen them, and help build a sustainable vision for our future.”

All four candidates have also said they back the concept of the Green New Deal, an ambitious energy plan introduced in the House in February by Rep. Alexandria Ocasio-Cortez Alexandria Ocasio-CortezWells Fargo CEO issues apology after saying there was a 'limited pool of Black talent' Brand responds to Trump claim protesters throw tuna cans at police: 'Eat em, don't throw em' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context MORE (D-N.Y.) that would transition the U.S. electric grid to 100 percent renewable energy by 2030. Every Democratic White House candidate in the Senate, including Sens. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (I-Vt.) and Kamala Harris Kamala HarrisHarris faces pivotal moment with Supreme Court battle Nearly 40 Democratic senators call for climate change questions in debates Joe Biden has long forgotten North Carolina: Today's visit is too late MORE (D-Calif.) have signed on as cosponsors.

Only O’Rourke and Inslee’s climate plans so far address the overall question of how to stop U.S. carbon emissions. Each proposal focuses on a duel purpose of moving the country off fossil fuels and investing in green jobs to grow the economy.

Inslee’s plan is similar to the Green New Deal in that it aims to completely transition to clean energy by 2030. But the governor also leaves open the door to using nuclear power, an energy sector to which some environmental groups are staunchly opposed.

O’Rourke’s plan, meanwhile, has generated criticism for not setting a shorter timeline to achieve emissions reductions. His proposal would invest $5 trillion to cut the country’s greenhouse gas emissions to net zero by 2050.

The Sunrise Movement, a youth action group that backs the Green New Deal, initially knocked that plan for not going far enough. Ocasio-Cortez told The Hill that it should be "more aggressive."

The Sunrise Movement later walked back the remarks, saying they came out "too hot" and support the direction of O'Rourke's plan, even if they want to see more. O'Rourke later committed to the group that he would not take campaign donations from the fossil fuel industry

The Sunrise Movement on Friday embraced Inslee’s climate plan, calling it a "spirited commitment to bold climate action that young people are looking for in our next president."

Inslee is the only Democratic candidate running his campaign entirely on climate action. Yet his relatively low name recognition as a Western state governor means he faces an uphill battle in the polls. While a focus on the leading issue of climate may work in his favor, he's not the only candidate looking for a green boost.

Inslee argues his plan is very achievable, and that his focus on climate change is more than a flash in the pan — a jab at his Democratic rivals.

“It is a plan that has shown a visceral commitment to [climate action]. Not just in the past 72 hours, but the past decade,” Inslee told The Hill in an interview.

“I’m the first and only candidate that announced this will be job No. 1,” Inslee said.

“It is the first priority, and the top priority, and my foremost obligation. It can’t be something you just do the first day. You have to do it everyday.”