NASA’s Parker Solar Probe is launched on at Cape Canaveral, Fla. (Jonathan Newton/The Washington Post)

NASA Administrator Jim Bridenstine said Wednesday that the agency is considering bypassing the long-delayed rocket it’s been building for years for its upcoming mission to the moon, instead considering commercial alternatives.

If that comes to fruition, it would mark a radical change from the way NASA had planned to return to the moon and would be a blow to the Space Launch System, involving a gigantic rocket that a government watchdog recently warned could cost as much as $9 billion.

Bridenstine’s comments, coming during a Senate committee hearing, show how NASA and the White House are getting frustrated with the slow pace of progress. The National Space Council, headed by Vice President Pence, has made a return to the moon a top priority, and officials have said the administration would like it to happen before the 2020 presidential election.

The Space Launch System was supposed to launch the Orion spacecraft in an uncrewed mission in orbit the moon no later than June 2020. But Bridenstine said the agency had recently been informed that there was going to be yet another schedule delay in what’s known as Exploration Mission-1, or EM-1.

“I think we as an agency need to stick to our commitments,” he said in a response to a question from Sen. Roger Wicker (R-Miss.). “Sir, if we tell you and others that we’re going to launch in June of 2020 around the moon, which is what EM-1 is, I think we should launch around the moon in June of 2020. And I think it can be done. We as an agency need to consider all options to accomplish that objective.”

The announcement was a blow for Boeing, one of the prime contractors on the SLS rocket, as it was facing serious repercussions in the wake of the crashes involving its 737 Max 8 airplane. The company did not immediately respond to a request for comment.

Boeing’s SLS rocket has repeatedly suffered schedule delays and cost overruns. In a scathing report last year, NASA’s inspector general found that the SLS program would require a massive amount of additional funding that could double the cost of the project to nearly $9 billion.

It found that Boeing had already spent $5.3 billion and was expected to burn through the rest of its budget three years ahead of time and without delivering a single rocket stage.

Bridenstine went out of his way to say NASA was not abandoning the rocket, praising it as “the largest rocket that’s ever been built in American history” and saying it remains “a critical capability” for the U.S. space program.

But the delays have forced the agency to look at using other rockets available. There are two that meet that criteria, officials said, the United Launch Alliance’s Delta IV Heavy and SpaceX’s Falcon Heavy.

To meet the 2020 timeline, Bridenstine said, the agency was looking at changing the mission profile. Instead of launching Orion on a trajectory straight to the moon, it would look at the possibility of flying it to orbit around the Earth. Then, on a second rocket, NASA would launch a propulsion module. The Orion spacecraft would dock with it, and the propulsion module would shoot Orion to the moon.

Bridenstine did not address how NASA would pay for those launches. And he said there is a major hurdle: Orion does not have the ability to dock in space.

“Between now and June of 2020 we would have to make that a reality,” he said.