More progressive lawmakers have begun vocalizing support for a so-called Green New Deal.

The Green New Deal is an economic stimulus concept designed to tackle income inequality and climate change. It’s modeled after President Franklin D. Roosevelt’s New Deal package of public works programs and projects created to help the economy during the Great Depression.

Over time, there have been differing opinions on just what a Green New Deal should tackle – and how it would meet its goals. However, some critics of the plan, including House Speaker Nancy Pelosi, have thrown some shade at the proposal.

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“It will be one of several or maybe many suggestions that we receive,” Pelosi told Politico on Feb. 6. “The green dream or whatever they call it, nobody knows what it is, but they’re for it right?”

A day later, Pelosi tweaked her tone, saying she hasn't seen the proposal but knows there's "enthusiasm" for the Green New Deal, adding it was "welcome."

Here’s a look at what lawmakers are supporting now, and what some earlier versions of the concept meant.

Seeing green in Congress

Progressive lawmakers are pushing for a sweeping “Green New Deal” in Congress – even garnering support among a growing number of Democrats considering a 2020 presidential bid.

A draft text of the plan circulating Congress includes a framework aimed at eliminating greenhouse gas emission from manufacturing and agriculture and “dramatically” expanding energy sources to meet 100 percent of power demand through renewable sources. The proposal describes this effort as a “historic opportunity to virtually eliminate poverty in the United States and to make prosperity, wealth and economic security available to everyone participating in the transformation.”

The proposal also calls for a job-guarantee program offering a “living wage job to every person who wants one,” a plan to aid workers affected by climate change, universal health care and basic income programs, among other things.

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Sen. Ron Wyden, D-Ore., has argued a Green New Deal needs to tackle the tax code – which he said is “stacked against renewable energy” – by eliminating breaks for oil companies. Instead, tax incentives should be made available for clean energy, clean transportation fuel and energy efficiency, he said.

Rep. Alexandria Ocasio-Cortez, D-N.Y., reignited the call for a Green New Deal during her surge to Congress in the midterm elections. Her plan is a lofty one, calling for the federal government to invest “trillions of dollars.” In turn, she says, “millions of high-wage jobs” will be created. She compared her plan to the Marshall Plan, or the European Recovery Plan, where the U.S. gave around $15 billion to help Western Europe recover in the aftermath of World War II.

To fund a Green New Deal, Ocasio-Cortez has suggested slapping a tax as high as 70 percent on the nation’s top earners.

Is green enough?

Critics have pushed back against the proposal, pointing to the price tag – estimated to be about $7 trillion – and global trends. Republicans have also decried the job guarantee included with recent Green New Deal plans, calling it a “deeply flawed policy” that would be detrimental to small businesses.

“The only ‘guarantee’ is a badly distorted labor market,” the Republican Policy Committee said.

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Chris Edwards, director of tax policy studies at the Cato Institute noted that the U.S. only emits a fraction of the global carbon dioxide emissions – meaning proposals included in the Green New Deal would only go so far in helping the climate without changes in other places, such as China or India.

Early Green New Deal ideas

Journalist Thomas Friedman floated the idea of a “green” economic proposal, writing in 2007, “I think that living, working, designing, manufacturing and projecting America in a green way can be the basis of a new unifying political movement for the 21st century.”

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“A redefined, broader and more muscular green ideology is not meant to trump the traditional Republican and Democratic agendas but rather to bridge them when it comes to addressing the three major issues facing every American today: jobs, temperature and terrorism,” Freidman said.

Obama, too, incorporated a “green plan” into his $825 billion economic stimulus package which targeted the efficiency of federal buildings and home improvement like added insulation. But his plan was regarded as lackluster and slow to start.

There was also Solyndra, a solar-panel maker that received $535 million in Energy Department loan guarantees during the Obama administration before it went bankrupt. It repaid only a projected $143 million of that money.

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Obama’s plan is a “classic example of why you don’t want the federal government getting involved in industry,” Edwards told Fox News.

Fox News' Brooke Singman contributed to this report.