Updated Wednesday at 12:45 p.m. with comments by senators in the Senate Committee on Environment and Public Works.

WASHINGTON — Kathleen Hartnett White, a climate change skeptic and former chairwoman of the Texas Commission on Environmental Quality, faced tough questions from Democrats on Wednesday during her nomination hearing for a top environmental post.

Democrats on the Senate Committee on Environment and Public Works grilled White about remarks she's made in her role as a fellow at the Texas Public Policy Foundation, a conservative think tank in Austin. They pressed White, who President Donald Trump nominated to head the Council on Environmental Quality, on her views over climate change, particulate matter and the Renewable Fuel Standard Program.

"It seems to me you don't believe climate change is real," Sen. Ben Cardin, D-Md., said to White. "You're not a scientist, are you?"

"No," White replied. "But in my personal capacity, I have questions that remain unanswered," adding that scientists need to have a more precise understanding of how much human activity impacts climate change.

Andrew Wheeler, a coal and nuclear lobbyist, was also part of Wednesday's hearing for his nomination to be deputy administrator for the Environmental Protection Agency. However, much of the three-hour hearing was focused on White.

Despite the tough questions she faced from Democrats, Wyoming Sen. John Barrasso, chairman of the committee, said he expects the committee will approve her nomination. After the committee's approval, White must be confirmed by the full Senate.

White's comments have also concerned environmental advocates, who sounded the alarm over her nomination to head the federal office that coordinates between agencies. Nearly 50 groups signed a letter Tuesday urging the Senate Committee on Environment and Public Works to reject her nomination.

Kathleen Hartnett White is director of the Armstrong Center for Energy and Environment at the Texas Public Policy Foundation.

"Ms. White has been a consistent science-denier regarding the overwhelming scientific consensus on human-fueled climate change, making her unfit to lead an office charged with coordinating how the federal government analyzes and discloses climate change impacts in environmental reviews required by the National Environmental Policy Act," says the letter, addressed to Barrasso and Tom Carper, the committee's top Democratic member from Delaware.

If nominated, White will join a number of Trump administration officials who doubt the scientific consensus behind human-caused climate change. On Wednesday, EPA Administrator Scott Pruitt told USA Today that a newly released government report blaming human activity for the rise of global temperatures does not impact his decision to roll back the Obama-era Clean Power Plan.

Sen. Jeff Merkley, D-Oregon used that report while questioning White, asking her to tell the committee which bar was the tallest in a chart showing the primary drivers of recent global temperature rise. The chart showed that "human activity" vastly outweighed "solar" and "volcanic" drivers to increased global temperatures.

.@SenJeffMerkley asks White to tell him which bar is the highest on graph showing driver of global temp rise. (It’s the red bar for human activity) pic.twitter.com/vB5K2i5SLL — Nicole Cobler (@nicolecobler) November 8, 2017

Her comments on climate change didn't seem to sway Republicans on the committee. Sen. Jim Inhofe, R-Okla., shrugged off Democrats, saying "all they want to talk about on the other side is global warming."

Carper blasted the president's nomination of White and other "climate deniers" the night before the hearing.

"While the rest of the world acts on climate change, @POTUS nominates climate deniers to top environmental jobs," he tweeted Tuesday.

While the rest of the world acts on climate change, @POTUS nominates climate deniers to top environmental jobs https://t.co/7qlLLuoYLT https://t.co/anvoZDH7qZ — Senator Tom Carper (@SenatorCarper) November 7, 2017

White was appointed to TCEQ by Gov. Rick Perry in 2001. She had previously been considered to head the Environmental Protection Agency.

"Throughout her career Kathleen has served Texans as a strong leader, in particular by ensuring that Texans have the energy and natural resources they need to prosper," Brooke Rollins, president and CEO of the foundation, said in a prepared statement after her nomination was announced in October. "We at TPPF congratulate Kathleen on this important opportunity and know she will serve our nation with the same thoughtfulness, determination and common sense that have been her hallmarks in Texas."

Since her departure from TCEQ, White has pushed back against the federal Endangered Species Act. In a paper for the Texas Public Policy Foundation, White called the act "antiquated" and "economically harmful without substantial environmental benefit" for Texas.

But environmentalists rejected the report. Stephanie Kurose, endangered species policy specialist at the Center for Biological Diversity, said White has "no qualms about letting wildlife go extinct" in a statement Tuesday.

"White is yet another Trump nominee for an environmental protection office who fanatically opposes protecting the environment," Kurose said. "In this post she could do incredible harm to our nation's natural heritage."

In other articles for the Texas Public Policy Foundation, White questioned human-fueled climate change and claimed carbon dioxide isn't a pollutant.

In a 2014 report, she asserted that "carbon dioxide has none of the attributes of a pollutant" and that calling it one "is absurd." White later praised carbon dioxide in a 2015 video, saying there are "beneficial impacts of carbon dioxide into our atmosphere."

She also has criticized renewable energy sources as "unreliable and parasitic" and EPA reports on the health benefits associated with reduced pollution as "statistical fiction."

"To confirm White for one of the highest environmental posts in our government would be deeply irresponsible," Kurose said. "Senate Republicans shouldn't rubber-stamp an industry puppet for such an important job."