Senator Bill Nelson (D-FL) slammed President Trump's NASA administrator nominee Jim Bridenstine for bringing partisan politics into NASA. (U.S. Senate)

Sen. Bill Nelson on Wednesday unleashed a blistering attack against Jim Bridenstine, the Trump administration’s nominee for NASA administrator, saying he not only lacks the technical and management experience but has been a partisan warrior whose behavior is an example of “why Washington is broken.”

During Bridenstine’s confirmation hearing Wednesday, Nelson, a Democrat from Florida, accused Bridenstine, a conservative Republican congressman from Oklahoma, of being a climate-change denier, backing legislation that discriminated against the LGBT community and acting as a divisive force in Washington.

“The NASA administrator should be a consummate space professional who is technically and scientifically competent and a skilled executive,” said Nelson, who wields great influence over the space agency, in his written opening statement. “More importantly, the administrator must be a leader who has the ability to unite scientists, engineers, commercial space interests, policymakers and the public on a shared vision for future space exploration.”

He added: “Frankly, congressman Bridenstine, I cannot see how you meet these criteria.”

Supporters of Bridenstine, a naval aviator and the former head of the Tulsa Air and Space Museum, have said that his views on climate change have evolved, and that he does not deny the effects of climate change. In his opening statement, Bridenstine said he would not only support NASA’s mission to explore space, focusing on a return to human spaceflight from United States soil, but continue to study Earth’s climate.

If confirmed, he said he would “look forward to promoting the scientific community’s priorities,” and support efforts “that increase our understanding of the Earth as a system and can enable solutions to the most pressing issues we face on our home planet.”

During the hearing, Bridenstine said he “absolutely” believes in climate change, that it is already having devastating effects and that humans contribute to it. But he demurred when asked whether human activity was the leading cause, saying more study was needed. In response to questions, he vowed to protect the integrity of NASA’s research, and to keep it an “apolitical” organization that should be driven by science, not politics.

Since being nominated, Bridenstine has received some high-profile endorsements, including from Sens. Ted Cruz (R-Tex.) and Richard C. Shelby (R-Ala.), but also from Buzz Aldrin, the second man to walk on the moon, and some key industry groups, such as the Commercial Spaceflight Federation. Sen. John Thune (R-S.D.), the chairman of the Committee on Commerce, Science and Transportation, said the committee would seek to move his nomination to the full Senate by as early as next week.

Even though Democrats "were trying to rough up the nominee," he predicted that "the votes will be there" for Bridenstine's confirmation.

In the House, where Bridenstine has served since 2013, he has been recognized as a leader on space issues and was the sponsor of a wide-ranging bill, known as the American Space Renaissance Act, which touched on national security and how to manage space debris and regulate the commercial space industry.

But a growing chorus of opponents have spoken out against him, including Sen. Patty Murray (D-Wash.), saying his opposition to same-sex marriage and the Violence Against Women Act made him unfit. “It is clear Representative Bridenstine would move us backwards not forwards,” she said in a statement, urging the committee to vote against his nomination.

Nelson said he was “offended” by Bridenstine’s comments criticizing Democrats and Republicans working across the aisle to pass legislation. He noted that Bridenstine had not only called former president Barack Obama “dishonest, incompetent and vengeful,” but that he has also supported the opponent of Sen. John McCain (R-Ariz.) in the GOP primary and attacked Sen. Marco Rubio (R-Fla.) for working with Democrats on immigration.

Bridenstine said that his activity as a congressman, representing the interests of his district, would be very different from the way he would act as NASA administrator. Politics, he said, has no part in the space agency. He also said that “I do believe, from my heart, that every human being has dignity and worth and each person should be treated as though they are a valued member of the team.”

But Nelson, the committee's ranking member, wasn’t convinced.

“NASA needs a leader who will unite us, not divide us,” he said. “Respectfully, congressman Bridenstine, I don’t think you’re that leader.”