WASHINGTON (AP) — President Donald Trump's nominee for NASA chief is promising to run the space agency on a consensus agenda driven by science.

Republican Rep. Jim Bridenstine's assurances, however, failed to placate Senate Democrats at a contentious confirmation hearing on Wednesday, with several revisiting the Oklahoma lawmaker's past statements on climate change, gays and immigrants and his brief management of a Tulsa museum that lost money during his leadership.

Florida Sen. Bill Nelson, the top Democrat on the Senate Commerce panel, called Bridenstine "divisive and extreme." Nelson highlighted Bridenstine's past statements attacking Democrats and fellow Republicans, Florida Sen. Marco Rubio, Arizona Sen. John McCain and former House Speaker John Boehner of Ohio, for bipartisan efforts.

"These are some of the most divisive tactics that this senator has ever seen in any party and this is just attacking people in your own party," Nelson said. "How do you keep NASA from being dragged down in a divisive political background?"

Bridenstine said politics ends for him when it comes to space and national security issues.

"I want to make sure that NASA remains, as you said, apolitical," he told Nelson.

Nelson and other Democrats said past NASA chiefs were not political and mostly scientists and ex-astronauts, but Bridenstine pointed to legendary NASA chief James Webb , who shepherded the Apollo program in the 1960s, as a veteran political appointee. If confirmed Bridenstine would be the first administrator who was a former elected legislator, but the U.S. Navy Reserve pilot said that shouldn't disqualify him.

Calling his fellow Oklahoman a leader on weather issues, Sen. Jim Inhofe quoted others and said, "It doesn't take a rocket scientist to run NASA."

Democrats pressed Bridenstine to acknowledge that humans cause global warming because of past statements of his that questioned the science. He did. He even explained a bit how carbon dioxide changes the climate.

"I'm happy to say it to anyone else because it's the truth," Bridenstine said. However, despite pressing by Democrats he wouldn't say whether humans are the main cause of climate change, which is what NASA says.

Bridenstine vowed not to allow politics to interfere with science even on climate change, even if the Trump administration insists.

"I think in the end the votes will be there," Senate Commerce, Science and Transportation Committee Chairman John Thune said. "The Democrats came trying to rough up the NASA nominee. That was pretty clear."

Sen. Gary Peters, D-Mich., questioned Bridenstine over his leadership of the Tulsa Air and Space Museum, noting that before Bridenstine ran the museum it had a surplus, but once he took over it had more than a $300,000 deficit.

Initially, Bridenstine said those numbers "are not true."

Later Nelson and Sen. Cory Booker, D-N.J., produced the IRS tax filings. Those filings show a $73,288 surplus in 2008 before Bridenstine and deficits of $311,655 in 2009 and $308,305 after Bridenstine was hired as director.

Bridenstine said it was the first time he had seen the filings in seven years and the museum was using cash reserves with the board's approval on big projects: an air show and a failed attempt to lure a retired space shuttle to Tulsa.

For his part, Bridenstine tried to focus on the agency's future not his past. He said that soon Americans will be launching to orbit on American-built rockets from the United States.

"I believe in this administration's vision of getting to Mars and using the moon as a proving ground," Bridenstine said.

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