Democratic presidential candidate and former vice president Joe Biden speaks during a campaign rally at Eakins Oval in Philadelphia on May 18. (Matt Rourke/AP)

Joe Biden is embracing the framework of the Green New Deal in his bid for the White House, calling on the United States to eliminate climate-warming emissions by no later than the middle of the century while creating millions of new jobs and rallying the rest of the world to forestall dangerous rising temperatures.

Biden released a 22-page climate plan Tuesday that appears at least in part aimed at blunting the criticisms of environmentalists and others on the left who have argued Biden’s 2020 presidential campaign is out of step with the current Democratic Party.

With the former vice president consistently leading in the polling, the Democratic Party’s left flank has leveled broader critiques of Biden’s record and campaign policies, including his vote for the Iraq War as a senator and his support for a public option rather than the universal “Medicare-for-all” plan.

“Biden has been trying to take somewhat of a centrist tack, but he has to appease the core of the base if he’s going to win the primary,” said Jim Manley, who served as an aide to former Senate majority leader Harry M. Reid (D-Nev.). “They’ve needed to start throwing down some solid policies that will appease the left.”

To that end, Biden’s climate plan adopts the rhetoric — and at times, many of the actual policy proposals — of the Green New Deal resolution put forward this year by Rep. Alexandria Ocasio-Cortez (D-N.Y.) and Sen. Edward J. Markey (D-Mass.), which calls on the nation to eliminate its carbon footprint by 2030.

Biden is trying to make his case on climate change — setting his own date for the nation to achieve net-zero emissions at 2050 at the latest — while vowing to help coal workers transition to a new clean-energy economy creating more than 10 million well-paying jobs.

“Biden believes the Green New Deal is a crucial framework for meeting the climate challenges we face,” the document reads.

“It powerfully captures two basic truths,” it goes on. The first is that “the United States urgently needs to embrace greater ambition on an epic scale to meet the scope of this challenge” and the second is that “our environment and our economy are completely and totally connected.”

But the campaign misstepped in another way on the plan after lifting language, often word for word, from environmental advocacy organizations in a sign for some progressives that he is not serious about the issue.

The campaign acknowledged Tuesday that portions of his climate plan had been copied without credit, saying that the lack of citations was inadvertent and that it had updated the document online.

Biden’s plan comes as a number of his rivals for the Democratic nomination have also begun to attempt to translate versions of the Green New Deal into policy documents. Gov. Jay Inslee (D-Wash.), who has based his whole campaign around climate change, recently released a $9 trillion plan to cut emissions, while former congressman Beto O’Rourke (D-Tex.) called for $5 trillion over 10 years to combat climate change.

And in the latest sign of momentum for the Green New Deal building among Democrats, Sen. Elizabeth Warren (D-Mass.) pitched on Tuesday a $2 trillion clean energy plan that involves a “Green Apollo Program” to invest in alternative energy and a “Green Marshall Plan” to encourage foreigners to buy U.S.-made green technologies.

The Sunrise Movement, a grass-roots climate advocacy group that helped pushed the Green New Deal to the center of Democratic politics, called Biden’s plan a “comprehensive” effort for tackling climate change — but also urged Biden to set a deadline earlier than 2050 for entirely decarbonizing the U.S. economy.

“This is a major victory for the tens of thousands of people who have raised their voices, but we’re keeping up the pressure,” said Varshini Prakash, co-founder of Sunrise.

Biden said on his first day in office he would rejoin the Paris climate accord, an international agreement brokered by the Obama administration in which nations voluntarily set goals for reducing greenhouse gas pollution. The Trump administration decided to pull the United States out of the agreement.

Biden’s campaign said a potential Biden administration would pressure other nations to get rid of subsidies for fossil fuels, to ban offshore drilling in the Arctic and to strengthen their emissions targets under the accord, though it did not provide precise levels.

In particular, Biden’s camp called out China for financing fossil-fuel projects throughout the world, adding that any future U.S.-China agreements would hinge on carbon mitigation.

Biden also calls for that commitment to achieve net-zero emissions by at least 2050 to be written into law but is vague on precisely how that goal would be achieved. Passing such a bill would be a tall order politically, even if Democrats take back the Senate as well as the White House next year.

A decade ago, the Obama administration unsuccessfully tried to pass into law its own enforcement mechanism for reducing emissions in the form of a cap-and-trade scheme that would have set up a market in which companies could buy and sell credits permitting them to release carbon into the atmosphere.

Biden’s climate plan leaves unsaid what exactly his enforcement mechanism would look like — whether it will be a cap-and-trade system, a carbon tax of the sort economists are increasingly embracing, or something else entirely.

As for the price tag, Biden’s plan says that his climate proposal would cost $1.7 trillion over a decade and that he would foot the bill by paring the 2017 Republican tax law provisions he says “enrich corporations at the expense of American jobs.”

But it is unclear if Democrats would be willing to raise that much money in new taxes from corporations, even assuming the party regains Congress and the White House. The Republican tax law lowered the corporate tax rate from 35 percent to 21 percent. Setting it at 27 or 28 percent, as Barack Obama and most congressional Democrats have called for, would only raise about $700 billion over 10 years, according to Marc Goldwein, senior vice president of the Committee for a Responsible Federal Budget, a nonpartisan think tank.

Biden’s plan says it will also be paid for by reducing incentives for tax havens, outsourcing and ending subsidies for fossil fuels, although is not specific about how much this would raise.

Conservatives are also likely to point out that Democrats have vowed to roll back Trump’s tax cuts on corporations to pay for multiple spending priorities that will cumulatively cost far more than the law itself, including new infrastructure projects and tax credits for the working class.

“This is the 100th different way Democrats will spend the revenue from repealing the Trump tax cut,” said Brian Riedl, an analyst at the Manhattan Institute, a right-leaning think tank. “The Trump tax cuts can be repealed only once, and you can’t spend it on every different liberal priority.”

In perhaps an acknowledgment of the difficult road through Congress for any Democratic president, the campaign noted a number of existing laws Biden could leverage to reduce emissions. His plan would reinstate methane pollution limits for oil and gas wells and tighten tailpipe standards for cars to ensure all new light- and medium-duty vehicles sold would be electrified.

Biden also calls for mounting an Apollo-style program to pour $400 billion into clean energy research over 10 years — an idea that may have some traction among a few congressional Republicans who are beginning to embrace innovation as the answer to climate change.

Biden’s plan embraces two specific energy technologies that some of the 2020 rivals have eschewed.

One is a method of skimming heat-trapping carbon dioxide from smokestacks called carbon capture. Biden is vowing to boost existing tax breaks for the nascent carbon-capture sector, though environmentalists dismiss the technology as only a way of extending the life of the fossil-fuel industry.

The other is nuclear energy, a long-standing form of power generation that today constitutes the largest portion of low-carbon electricity in the United States. But the industry faces an uncertain future as cheaper forms of power, such as natural gas and renewable energy, eat away at its market share.

Sen. Bernie Sanders (I-Vt.) is calling for a complete phaseout of nuclear energy over concerns of radioactive waste storage and the risk of meltdowns. Biden instead wants to put money toward developing the new generation of small modular nuclear reactors in addition to addressing safety concerns.

Biden’s plan also does not mention a potential ban on fracking and has already been criticized by some environmentalists for not going far enough.

“This plan embraces dangerous nuclear power, environmentally-harmful biofuels, and foolish dreams of carbon capture and sequestration that will lock in our continued dependence on fossil fuels,” said Erich Pica, president of Friends of the Earth Action, an environmental group, in a statement. “Like most candidate climate plans, it barely addresses agriculture and the U.S.’s international obligations as the world’s largest historic emitter.”

Some of Biden’s rivals for the Democratic nomination — including Sanders, who in most polls is No. 2 to Biden, and Inslee, who is basing his entire campaign around climate change — lambasted Biden’s climate politics after Reuters reported that Biden was seeking to chart a “middle ground” on climate policy.

Biden aides denounced the story as inaccurate, but it set off a firestorm on the left from those who said it revealed the vice president was not prepared to confront the scale of global climate change.

At some points, Biden’s climate plan contradicts some of his past positions. His plan, for example, calls for an end to new oil and gas permitting on public lands and waters, even though a decade ago Biden said he was “not opposed to drilling” and indeed was part of an administration that once tried to expand drilling in the Atlantic.

But at least one of Biden’s passions — railroads — is apparent in the plan.

The former senator from Delaware, who commuted so often between Washington and his home in Wilmington that he was nicknamed “Amtrak Joe,” calls for cutting the commuting time between Washington and New York by half and for making progress on a high-speed rail project connecting Los Angeles and San Francisco.