WASHINGTON — President Donald Trump has ordered the Pentagon to start work on a new, sixth military service dedicated to space, but that seems unlikely if Democrats take the House in midterms on Tuesday.

On the flip side, two key Space Force opponents on Capitol Hill are facing tough battles to hold onto their seats: Democratic Sen. Bill Nelson of Florida and Republican Rep. Mike Coffman of Colorado.

“I’m going to take the administration on for Space Force,” Coffman, chairman of the House Armed Services Military Personnel Subcommittee, told the newspaper Westworld last month.

“The president wants to create a whole new department of space, and if that requires authorizing language in the Armed Services Committee, I expect to lead the effort to kill that in committee,” he said.

Coffman had represented his suburban Denver district for a decade, but it went to Democratic presidential candidate Hillary Clinton in 2016. And this year, he has worked to distance himself from the president — over immigration, gun laws and Space Force.

Coffman said he could support a “space corps” subordinate to the Air Force, but he told Defense News in September that Trump’s Space Force proposal is “a really bad idea” that would reverse gains in trimming Pentagon bureaucracy “for no real value.”

“I feel confident we can block this. The president will not have the votes,” he said.

But Coffman is in danger. He faces Democrat Jason Crow in a district that Clinton carried by 9 points in 2016. The Congressional Leadership Fund, the super PAC backed by House GOP leadership, cut its spending in September — an ominous sign.

In Florida, home to Air Force Space Command’s 45th Space Wing, Nelson has ripped Trump’s plan to shake up the status quo. Nelson is the top Democrat on the Senate Armed Services Cybersecurity Subcommittee, a former astronaut and a key voice on space policy.

“The president told a US general to create a new Space Force as 6th branch of military today, which generals tell me they don’t want,” Nelson wrote on Twitter, after Trump made an initial announcement in June. “Thankfully the president can’t do it without Congress because now is NOT the time to rip the Air Force apart. Too many important missions at stake.”

In spite of Trump and Vice President Mike Pence campaigning for Nelson’s GOP challenger, Gov. Rick Scott, Nelson was holding onto a slim lead into Tuesday’s vote. In an NBC/Marist poll released Monday, Nelson would gets 50 percent of the vote and Scott would get 46 percent, a narrow 4-point lead for Nelson.

The administration is expected to seek approval from Congress, where Nelson and Coffman have not been alone in their skepticism. A major reorganization of the military would have to be authorized by the annual defense policy bill, which is hammered out each year by both chambers’ armed services panels, and funded through both chambers’ appropriations bills.

If the House falls under Democratic control, as is widely projected, it would make a vocal opponent of Space Force — Rep. Adam Smith, D-Wash. — the HASC chairman. Currently the ranking Democrat, Smith came out against Trump’s proposal in a statement in September.

“I am concerned that his proposal would create additional costly military bureaucracy at a time when we have limited resources for defense and critical domestic priorities, and I do not believe it is the best way to advance U.S. national security,” he said. "We must do a better job of dealing with space as a national security priority. I will continue to work toward a smarter, more effective approach.”

Smith’s counterpart on the Senate Armed Services Committee, Sen. Jack Reed, D-R.I., said in August that Space Force “is not the way to go.” While the GOP is expected to retain control of the Senate, Reed and Smith could join forces in defense policy bill negotiations.

Nelson led the opposition last year when a bipartisan proposal for a space corps that predated Trump’s proposal was cut from the 2018 defense policy bill, despite support from HASC leaders, including Chairman Mac Thornberry, R-Texas. That proposal was for a new service subordinate to the Air Force.

Alabama Republican Rep. Mike Rogers, the Strategic Forces Subcommittee chairman who proposed the idea then, has argued that the Air Force was prioritizing its fighter jets over space, and the U.S. needs a dedicated service to stay ahead of China and Russia in what many see as the next frontier of warfare.

The proposal is aimed at protecting American satellites, Rogers said, and “not George Jetson getting on a rocket coming out of his suitcase.”

Defense Secretary Jim Mattis and Air Force leaders opposed the idea then, but they have publicly fallen in line behind the Trump administration, which unveiled plans in August to establish the service by 2020.

Capitol Hill skeptics, including Coffman, have found ammunition in an Air Force that estimates a new service would cost $13 billion over five years.

The strategic forces subpanel’s ranking Democrat, Rep. Jim Cooper, expressed during a recent Aspen Institute event with Rogers skepticism of that estimate, which included a $1 billion headquarters.

A Space Force proponent, Cooper also expressed hope Trump’s support would not “ruin the debate” over what he sees as a common-sense proposal.

“The president’s unexpected intervention needlessly politicized it," Cooper said, “because it’s never been political.”

Joe Gould was the senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry. He had previously served as Congress reporter.

More In Congress