Republican presidential candidate Sen. Ted Cruz, R-Texas, greets supporters during a campaign event, Dec. 4, 2015, in Johnston, Iowa. Scott Olson/Getty Images

World leaders attending a global environmental conference in Paris this month may agree that climate change is a real threat, but Republican presidential candidate Sen. Ted Cruz of Texas -- and his biggest campaign contributors -- aren’t convinced. As United Nations negotiations over how to address global warming continued in France, Cruz scheduled a hearing Tuesday that seeks to undermine the general urgency of the Paris climate summit while simultaneously supporting the position of some of his wealthiest donors.

The hearing, titled "Data or Dogma? Promoting Open Inquiry in the Debate over the Magnitude of Human Impact on Earth's Climate," will feature several climate scientists -- some of whom are climate change doubters -- from U.S. universities, including from Princeton, Georgia Institute of Technology and the University of Alabama in Huntsville. The focus will be federal funding for climate change researchers and whether political pressures suppress opposing scientific viewpoints.

Cruz is the third-biggest fundraiser in the 2016 presidential field so far, and a large chunk of that cash has come from the country’s largest energy companies, the ones that extract, transport, process and sell fossil fuels. The senator and the energy industry have both been critical of an Environmental Protection Agency initiative, known as the Clean Power Plan, which is favored by U.S. President Barack Obama and would curb the amount of greenhouse gas emissions from power plants.

The National Mining Association -- which calls itself the voice of American mining -- and Cruz have adopted almost identical rhetoric in response: The regulations will drive up costs for consumers and make the electric grid less reliable. For Cruz, the EPA rules are also flat-out unconstitutional.

"The nation’s electric grid will become far less diverse and reliable, and far more costly, with this proposal to replace lower-cost sources of electricity with more expensive and less reliable sources," Hal Quinn, the CEO of NMA, said in June 2014 after the EPA plan was announced. "In asking the states to implement this proposal, EPA is demanding their complicity in raising the cost of a vital energy source for all Americans."

"The President’s lawless and radical attempt to destabilize the Nation’s energy system is flatly unconstitutional and – unless it is invalidated by Congress, struck down by the courts, or rescinded by the next administration – will cause Americans’ electricity costs to skyrocket at a time when we can least afford it," Cruz said in a statement posted to his 2016 campaign website. "I urge leaders of both parties, including Democrats who represent communities that will be devastated by this reckless policy, to stand up against this Administration’s dangerous agenda of economic decline."

Democrats, however, say that the stakes are too high to block the president’s Clean Power Plan and other efforts to rein in climate change. The White House says that the plan will save U.S. consumers $85 a year on their energy bills and will create $54 billion in public health and climate benefits. The White House also says 90,000 child asthma attacks will be avoided and that there will be 3,600 fewer premature deaths.

The plan is part of a larger effort by the Obama administration to cut emissions in the U.S. and internationally. The Paris climate talks, which Obama has endorsed, could be a crowning event for the president's legacy should negotiators broker a workable deal among the 190 governments in attendance to cut greenhouse gas emissions.

Cruz has received nearly $2 million from the oil and gas industry since 2011, including $709,493 that has gone into his presidential campaign coffers since he began his run for the presidency earlier this year, according to data compiled by the Center for Responsive Politics. The National Mining Association gave $10,000 to Cruz’s Senate campaign in the 2012 cycle, making him a top-20 recipient. The well-known Koch Industries, a privately held conglomerate that has significant oil interests and is connected to the billionaire Koch brothers, gave $23,750 to Cruz in the 2012 cycle. A Koch-backed group that rates presidential candidates recently named Cruz as the only "climate hero" in the 2016 field.

Cruz has surged in polls recently and on Monday overtook real estate mogul Donald Trump in Iowa. That marked the first time that Cruz has held first place in a poll in the 2016 presidential race and also one of the first times that Trump had fallen behind in polls since he surged following his campaign announcement.

John Podesta, campaign chair for Democratic front-runner and former Secretary of State Hillary Clinton, released a statement Tuesday in response to Cruz’s planned hearing, saying that “there is nothing heroic about blocking measures that would keep our kids and communities healthy.” Podesta also said the EPA regulations would be far more beneficial than the White House says: The Clean Power Plan will prevent as many as 150,000 asthma attacks in children and 6,700 premature deaths a year, he cited.