Before Rep. Jim Bridenstine was nominated to lead NASA, he already had unorthodox ideas about what it should do. In 2016, as one of Oklahoma’s congressmen, he proposed the American Space Renaissance Act, which he called a “pioneering doctrine” that would refocus NASA’s mission. The space agency would concentrate on human spaceflight and “permanently secure the United States of America as the preeminent spacefaring nation.” Bridenstine’s vision would eliminate two of NASA’s current stated missions — to pursue aeronautical and space activities for peaceful and scientific purposes, and to expand knowledge of Earth and its atmosphere. (Bridenstine has said that there’s no credible evidence that CO2 affects the global climate.) In their place, his plan would spread human influence throughout the solar system and ensure the U.S. shows up first on alien worlds — and gets them ready for use by humans.

Bridenstine never really expected his legislation to pass in its entirety. But as President Trump’s nominee for NASA administrator, he may still get a chance to realize his vision. On Wednesday, he’s likely to face tough questions from senators wondering if a 42-year-old former Navy pilot and climate skeptic with an enthusiasm for space but no technical background or formal connection to NASA is really the right man for the job.

His nomination was widely expected in both Washington and the aerospace community, and Florida’s senators both opposed him out of the gate. Republican Marco Rubio and Democrat Bill Nelson, the latter a former astronaut, both lamented the choice of a politician for the job, rather than someone with deeper NASA ties. Bridenstine could be “devastating for the space program,” Rubio told Politico. “It’s the one federal mission which has largely been free of politics, and it’s at a critical juncture in its history.”

Objections from senators in Florida and other states likely stem in part from Bridenstine’s support for so-called “new space” companies like Elon Musk’s SpaceX, Jeff Bezos’ Blue Origin, and others. Giving beefy NASA contracts to those upstarts could reduce the number of jobs available at rocket plants managed by Boeing, Lockheed and other “legacy” companies — which employ workers in Florida, Alabama, Colorado, Texas, Washington and other states. Meanwhile, Republican senators Ted Cruz of Texas and Richard Shelby of Alabama have lined up in support. Shelby said on Twitter that he met with Bridenstine and the senator looks forward to “supporting him throughout this process.”

Probably the most noteworthy endorsement came Sept. 20 from Buzz Aldrin, the Apollo 11 astronaut and space-exploration rabble-rouser, who coauthored an endorsement in the industry magazine Space News saying Bridenstine’s space renaissance act “offers a clear and workable plan.”

But Bridenstine’s nomination has also caused alarm among environmental groups, climate advocates, and others concerned about statements he has made about climate change — for instance, falsely saying that global temperatures stopped rising 10 years ago. Such views could have important consequences, because about 10 percent of NASA’s budget — $1.9 billion, according to Climate Central, of the $19.65 billion allotted to the agency in 2017 — is spent on climate research.

Ohio Sen. Sherrod Brown, a Democrat whose state hosts NASA’s Glenn Research Center, condemned Bridenstine’s nomination in an email to campaign supporters, according to CNN. “He has no experience in scientific research or academia. He’s even expressed doubt that humans contribute to climate change — a research area in which NASA is intimately involved,” Brown wrote.

Ellen Stofan, who studies Mars and Titan and was NASA’s chief scientist under Obama, said Bridenstine’s written questionnaire submitted with his nomination suggested a more positive view of science than his previous statements. “He talked a little bit about the balance between planetary science and Earth science. But I don’t think you would find a planetary scientist who wouldn’t talk about the critical importance of using satellites to study this planet,” she said. “Climate change is the biggest challenge we face right now as a country, and NASA plays a key role in helping us understand this planet. We would hate to see that be cut in any way.”

NASA’s budget and priorities are set by the White House and implemented by the administrator, assuming Congress approves the funds. It has four areas of focus: aeronautics, which puts the first A in NASA’s acronym; human exploration, which includes the International Space Station; science, which includes Earth science, planetary science, astrophysics, and heliophysics; and space technology. NASA’s overall budget has remained fairly steady in the past few years, but that money has shifted among these four divisions, which NASA calls “directorates.” One directorate’s funding might go up while another goes down. Those shifting funds reflect changing priorities, but an administrator’s vision sets the tone for the whole agency, said Phil Larson, assistant dean for the school of engineering at the University of Colorado-Boulder and a former Obama White House science official. “The 17,000 NASA civil servants look toward that leadership for what their day-to-day should be focused on.”

Bridenstine’s past statements and questions during congressional hearings indicate that he’d like NASA to focus on the moon first and Mars later — in part because China prioritizes the two missions that way, too. In a February committee hearing, Bridenstine noted China’s successful lunar orbiter, and said the space between Earth and the moon is “critically important for the geopolitical position of the United States.” By contrast, he described a crewed Mars mission as a “horizon goal.”

In this, Bridenstine appears to be aligned with the National Space Council, a group led by Vice President Mike Pence that coordinates spacefaring interests among NASA, the Defense Department, and other agencies. The council had been formed and was disbanded twice before, most recently in the 1990s, but President Trump resurrected it. At the council’s first meeting, on Oct. 5, Pence announced a renewed focus on future moon missions, though there was no discussion of funding.

More so than the heads of other science agencies, the NASA administrator plays the role of arbitrator — between NASA and the White House, but also among the agency’s four divisions, said Casey Dreier, director of space policy for the Planetary Society. By law, the directorates’ funding is separated, and NASA can only move about 5 percent of its money around before Congress must get involved, Dreier says. A NASA administrator plays a major role in how and where those funds initially settle. “That’s where the NASA administrator really makes a difference. They choose, what do we push back on, if Congress doesn’t line up with our priorities? What’s most important to the agency?” Dreier said.

Since the Apollo era, NASA’s budget has generally tracked with fluctuations in overall discretionary spending, Dreier said. But while Congress holds the purse strings and can adjust the budget in ways that go against the White House’s wishes — which happened earlier this year when a Senate committee restored Trump’s proposed cuts to NASA education programs and other projects — the White House request, and thereby the administrator’s statements, can dramatically affect policy, Dreier said. “Unless something is specifically countermanded or specified, generally the process will default to the White House position. There is power in that request.”

Space policy experts have met with Bridenstine privately in the weeks since his nomination became official, and they say Bridenstine is engaged, asks detailed questions, and seems interested in NASA’s mission. “With NASA’s global leadership, we will pioneer the solar system, sending humans back to the moon, to Mars, and beyond,” Bridenstine wrote in a lengthy questionnaire delivered as part of his nomination.

“He’s personally engaged and interested in space, and he wants the job,” Dreier said. “There is a benefit to not having any intrinsic personal engagement with the field, because you don’t bring in those conscious or unconscious biases with you.”

Larson, a veteran of both the Obama administration’s Office of Science and Technology Policy and SpaceX, said the confirmation hearing this week will be the true test of where Bridenstine stands.

“For an Obama administration official, I am fairly bullish on his appointment, mainly because (a) I think it could be a lot worse, and (b) he does seem to have a passion for these issues,” Larson said. “But his confirmation hearing will be important for getting him on the record on climate change. Obvious questions about climate change require obvious answers from a potential leader of NASA, so that’s where you will see senators like Nelson using that opportunity to look under the hood.”

Determining a long-term goal for NASA could be a central pillar for the Trump administration — to the extent that big change is possible in his first term, what with the 2018 budget process lagging behind and the 2019 budget process already under way. Bridenstine will have to grapple with how and whether his actions and statements could polarize NASA, one of the nation’s most popular government agencies.

“NASA tends to be still nonpartisan, and it’s because NASA is kind of a rare area, where it still has parochial politics impacting it,” Dreier said. “You have this base-level commitment to NASA from a wide variety of people from across the ideological spectrum, which gives it an unusual amount of strength to continue pursuing amazing things.”

CORRECTION (Oct. 31, 2017, 2:53 p.m.): An earlier version of this article gave the incorrect home state of Sen. Richard Shelby. He represents Alabama, not Louisiana.