Democratic presidential candidate Beto O’Rourke, trailing in the polls despite a high-profile campaign launch, sought to prove his policy chops by unveiling a $5 trillion plan to battle climate change and reach net zero carbon emissions in the U.S. by 2050.

“The greatest threat we face — which will test our country, our democracy, every single one of us — is climate change. We have one last chance to unleash the ingenuity and political will of hundreds of millions of Americans to meet this moment before it's too late,” the former three-term congressman from Texas warned as he unveiled his proposal Monday.

BIDEN TOPS O'ROURKE, SANDERS, FOR LARGEST FIRST DAY HAUL

O’Rourke’s plan – his first major policy rollout since launching his presidential campaign in mid-March – calls for “mobilizing” $5 trillion over 10 years to transform the nation’s aging infrastructure and spur innovation to help communities lead the fight against climate change. O’Rourke’s campaign calls the price tag the “single largest investment in fighting climate change in history.”

According to a proposal released by his campaign, O’Rourke would leverage $500 billion “in annual government procurement to decarbonize across all sectors.”

The candidate says he’ll pay the bill for his plan with $1.5 trillion from "revenues generated by structural changes to the tax code that ensure corporations and the wealthiest among us pay their fair share and that we finally end the tens of billions of dollars of tax breaks currently given to fossil fuel companies,” according to his campaign’s release.

The proposals also calls for executive actions on the his first day in the White House to “start cutting pollution across all sectors of the U.S. economy,” and working with Congress to produce a “legally enforceable standard” to make sure the U.S. achieves net-zero emissions by 2050 -- and getting halfway toward that goal by the end of the next decade.

O’Rourke also promises to take “significant actions” to defend communities deal with fires, floods, droughts, hurricanes and other threats spurred by climate change.

Republicans, though, dismissed the proposal as a costly bid to "impress" coastal elites.

“Beto’s $5 trillion in new government spending is strictly designed to impress his chardonnay swilling coastal elite friends. The fact is the money has to come from someone and taxpayers across the country are not going to foot the bill for Beto’s crazy plans,” Republican National Committee spokesperson Mandi Merritt said in a statement.

O'ROURKE SAYS HIS CAMPAIGN'S IN A 'GOOD PLACE'

On the day he launched his White House bid, O’Rourke strongly endorsed the Green New Deal, the sweeping proposal that aims to transform the country’s economy to fight climate change -- while enacting a host of costly new health care and welfare programs.

The measure has been backed by many of the 2020 Democratic presidential contenders since it was announced in January by freshman rising star Rep. Alexandria Ocasio-Cortez of New York and veteran Sen. Ed Markey of Massachusetts.

Campaigning in Iowa hours after declaring his candidacy, O’Rourke stressed that "not to be dramatic, but literally, the future of the world depends on us right now here where we are."

O’Rourke continues to regularly bring up the issue on the campaign trail.

O’Rourke is spotlighting his plan during a swing through California. On Sunday, he met with Mariposa County firefighters who’ve been battling wildfires. And on Monday, he’s taking a walking tour at Yosemite National Park before holding a climate change roundtable at Modesto Junior College.

O’Rourke surged out of the gate, with large crowds, soaring poll numbers, and an eye-popping $6.1 million in fundraising during his first day as a candidate. But his poll numbers, as well as media attention, faded after just a couple of weeks, though O’Rourke continues to draw healthy crowds on the campaign trail.