Kathleen Hartnett-White, President Donald Trump’s pick to lead the Council on Environmental Quality, was just one Senate vote away from becoming the White House’s top environmental adviser.

But late Thursday night, the controversial former Texas regulator returned to square one.

The Senate sent her nomination back to the White House as part of a deal to close out the legislative session before the holidays. Earlier this week, Democrats mounted a last-minute effort to exclude Hartnett-White from any agreement to table nominations and pick up where they left off in the confirmation process when the Senate reconvenes in January.

Trump is now required to re-nominate her, forcing Hartnett-White to start the process over, including a new vote before the Senate Environment and Public Works Committee. The panel narrowly voted along party lines on Nov. 29 to advance her to the full Senate despite a bruising hearing at which she struggled to answer basic science questions and repeatedly contradicted herself. Videos of her stammered responses went viral.

The decision to send her nomination back makes Hartnett-White the second major environmental pick to crater this month. Less than two weeks ago, Michael Dourson, Trump’s pick to lead the Environmental Protection Agency’s chemical safety division, withdrew his name from consideration after two Republican senators signaled they planned to vote against his confirmation. Democrats and environmentalists adamantly opposed Dourson, a researcher whose work often bolstered the safety claims of the tobacco companies and chemical manufacturers that paid him.

Senate EPW Kathleen Hartnett-White endured a humiliating confirmation hearing at which Democrats peppered her with questions that should be softballs for an environmental policy wonk, such as how the oceans absorb carbon dioxide and whether the planet is warming.

“While we have been able to make progress in recent weeks on several qualified and reasonable environmental nominees, others, like Kathleen Hartnett White and Michael Dourson, have proven far too extreme to hold such important positions or be confirmed by the Senate,” Sen. Tom Carper (D-Del.), who led the charge against Hartnett-White, said in a statement late Thursday.

“I am pleased that Ms. White’s nomination has been returned to the White House,” he added, “and I am hopeful that President Trump will seize on the opportunity to start the new year and the new session of Congress off on the right foot by nominating a new and better qualified candidate to lead this consequential office.”

The White House did not respond to a request for comment on Friday morning.

Sen. Sheldon Whitehouse (D-R.I.), one of the Senate’s foremost climate hawks, called Hartnett-White’s nomination “a failed experiment,” noting that Democrats found evidence that she plagiarized her written responses to questions ahead of the confirmation hearing.

“Ms. White didn’t know basic science,” Whitehouse told HuffPost in an email on Friday. “She gave some of the most embarrassing hearing testimony I’ve ever seen.”

Hartnett-White defended carbon dioxide, one of the chief causes of man-made global warming, as a “harmless trace gas” and “plant food,” compared Pope Francis’ public calls to reduce greenhouse gas emissions to the Catholic Church’s arrest of Galileo for heresy in 1633, and derided the shift to renewable energy as “green folly” and “a false hope.” Her one-term tenure as Texas Commission on Environmental Quality chair was marked by her decision to greenlight a new coal-fired plant over the objections of 24 Dallas-area cities and counties.

There’s almost no real environmental problems. Kathleen Hartnett-White

Last month, more than 300 scientists signed a letter demanding the Senate reject her on the grounds that “one thing more dangerous than climate change is lying.”

“Kathleen Hartnett-White was laughably unqualified, even for Trump,” Alyssa Roberts, a spokeswoman for the League of Conservation Voters, told HuffPost by phone on Friday. “She clearly didn’t have enough support in the Senate and Trump should reconsider his approach and nominate someone who will prioritize protecting clear air and water instead of a fringe anti-science zealot.”

No Republicans publicly opposed Hartnett-White. But her history of taking extreme stances to defend polluters could give lawmakers some pause if she is re-nominated.

She railed against Republicans for failing to campaign on the idea that the nation has “almost no real environmental problems.” “What you never hear and regrettably not even from our side is there is no environmental crisis,” she said in 2011 at an Americans for Prosperity conference titled, “The EPA’s Job Crushing Regulatory Assault.”

Despite World Health Organization estimates that peg the number of worldwide deaths per year from particles in the air at 3 million, she said “people do not die from particulate matter levels.”

An ardent coal advocate who credited the fuel with abolishing slavery, Hartnett-White attacked the EPA’s rules to limit mercury pollution from coal-fired power plants.

For Republicans like Sens. Lamar Alexander (R-Tenn.) and Susan Collins (R-Maine), who have fought to clean up mercury contamination, that could raise concerns. Neither lawmaker returned HuffPost’s requests for comment on Tuesday.

This story was updated to include comment from Whitehouse.