Long before President Trump introduced his Space Force vision as an applause line at political rallies, the top administration official who would be selected to oversee its creation came out decisively against a similar plan.

Air Force Secretary Heather Wilson said in a visit to Capitol Hill in June 2017 she opposed the creation of a “Space Corps,” a service some lawmakers had proposed to oversee military operations in space.

“The Pentagon is complicated enough. We’re trying to simplify. This will make it more complex, add more boxes to the organization chart and cost more money,” she said. “If I had more money, I would put it into lethality, not bureaucracy.”

Less than two years later, Wilson finds herself leading a similar effort directed this week by the president.

As Air Force secretary, Wilson has for the past two years led a department that includes about 321,000 active-duty airmen and has a budget of more than $156 billion. Initially recruited by former Pentagon chief Jim Mattis, she has focused on building up the readiness of Air Force squadrons to deploy after years of congressionally mandated budget cuts. But her role is likely to become even more prominent in coming months, following the Trump administration’s decision to put her in charge of the Space Force.

Wilson’s name also has been floated by some lawmakers as a contender to become the next Pentagon chief, two months after Mattis resigned in protest of Trump’s policies and the president replaced him on an acting basis with Deputy Defense Secretary Patrick Shanahan.

Like the Space Corps idea that Wilson, Mattis and other Pentagon officials fended off in 2017, the new Space Force proposal calls for the creation of a new branch of service within the Air Force Department, complete with a four-star general joining the Joint Chiefs of Staff. But it is smaller than the Space Force plan Trump originally conceived, which also called for a separate Department of the Space that would have been led by an appointed service secretary, rather than falling under Wilson’s purview.

The political realities for the Pentagon changed after Trump announced at a National Space Council meeting in June 2018 he wanted a Space Force, a “separate but equal” branch of the armed forces. The plan now needs approval by Congress.

Wilson said Thursday that when the president sends his 2020 budget proposal to Congress in coming days, it will include draft legislation for the Space Force. She defended the idea, saying Trump had prioritized its development at a time when adversaries seek to deny the United States the use of space in times of crisis or war.

“I’m the secretary of the Air Force. I don’t have the same kind of power of the presidency that the White House has,” she said, answering a question from The Washington Post on C-SPAN’s “Newsmakers” program.

“By bringing this forward and saying, ‘We’re going to do something different. We’re going to create a new force. We’re going to do it in a cost-effective way,' the president has made this kitchen-table conversation, and he has made it a central element of what he wants to do as president of the United States,” she said. “So, kudos to him for bringing this to the fore in a way that it really wasn’t before."

Wilson’s favoring U.S. military investment in space isn’t a surprise. The service has warned about national security issues there for years and released a report recently that laid out a scenario in which anti-satellite weapons increasingly are becoming a threat to national security.

How the administration goes about focusing on space has been more of a friction point.

Last fall, Wilson signed a memo that stated the cost of starting a Space Force Department and U.S. Space Command would be about $13 billion over five years. Some Space Force proponents and budget analysts questioned whether the number was inflated.

Wilson said Thursday that the internal Air Force plan included a full Space Force Department, rather than a Space Force service, a distinction that will make the new service leaner and place it on even footing with the Marine Corps, which is part of the Navy Department.

By creating a service along those lines, the money needed to start a Space Force will be “substantially less” than the Air Force plan last fall, she said, without providing a new figure.

In an internal “pre-decisional” memo obtained by The Washington Post, the new Space Force estimates are dramatically different: between $72 million and $73 million per year, with other costs remaining in the broader budget for the Air Force and Pentagon.

But a defense official, speaking on condition of anonymity due to the sensitivity of the discussions, said the figure was “artificially straight-lined” in budget documents, and the Defense Department plans to explain to Congress that the overall cost of a fully operational capable Space Force will be “somewhat north” of $500 million per year. Those figures are roughly in line with estimates by Todd Harrison, a budget analyst with the Center for Strategic and International Studies who predicted the new costs would be between $300 million and $550 million per year.

Wilson said she expects there will be discussions for months about the new Space Force proposal and possibly congressional hearings. It would be “unwise” at this point to speculate whether Congress will be receptive to the new plan, she said.

Wilson, a former New Mexico congresswoman, Air Force officer and university president, already has coped with rumors reported by Foreign Policy magazine that the president was angrily considering replacing her because of how she had handled the issue.

Rep. Mike D. Rogers (R-Ala.), who along with Rep. Jim Cooper (D-Tenn.) proposed the Space Corps in 2017, said in an interview with the Opelika-Auburn News that the rumors were “a shot across the bow” after “the White House found out she was working against it.” Rogers said he thought she had become more supportive.

Wilson declined to say whether she was committed to serving in her current job and would not say on C-SPAN whether she would accept an offer to become defense secretary. Her focus, she said, is taking care of the Air Force.

Wilson, in an interview with The Post, cited “Dead Poets Society” when asked about her future. In the film, an English teacher played by Robin Williams urges students to seize the day.

“Tomorrow is really uncertain,” Wilson said. “I don’t mean that in a professional way, I just mean that you never know. All you have is today. What are you going to do today? And that’s all any of us have. I try to guide the Air Force to the future, but I think any of us that [say they] know what will happen tomorrow or next week are kidding ourselves about what it means to be human. We don’t have any certainty in life, and I always live my life that way.”

Wilson and Gen. David L. Goldfein, the Air Force’s chief of staff, also say the service needs to grow to match a national defense strategy Mattis released last year focusing more heavily on preparing for adversaries like Russia and China and less on counterterrorism operations.

“The operational squadron is really the fist of the United States Air Force,” she said. "Our analysis says to execute the National Defense Strategy, we need 386. We can quibble about whether it’s 386 or 390 or 375, but the Air Force is too small for what the nation is asking it to do.”

One issue decided recently: The Air Force will buy new F-15 CX aircraft, Wilson said. The decision, first reported by Bloomberg in December, will provide the Air Force with new “fourth-generation” fighters even as it prioritizes the stealthy “fifth-generation” F-35, a more advanced aircraft.

Wilson said in an interview with Defense News in September that she thought the Air Force should focus on spending its money on F-35s. Other senior leaders at the Pentagon, including Shanahan, pressed to buy both.

Wilson told The Post that the service needs to grow from about 55 fighter squadrons now to 62 by 2030. The question is how to get there.

“Now, you can argue and say, ‘Why don’t you just buy more F-35s?’ ” Wilson said. “You get fewer of them, and they do cost more to maintain, and Lockheed Martin hasn’t driven down the sustainment costs as fast as we wanted. So it’s, okay, what’s the best use of the money if you are adding money for tactical air, and how do we modernize this fleet?”