The Pentagon plans to create a new military command responsible for war fighting in space, but opposition in Congress could block a more ambitious “space force,” a new military service that President Trump has endorsed repeatedly in tweets and campaign rallies.

Trump’s idea for a futuristic space service has raised deep concerns among some military officials and senior Pentagon commanders, especially in the Air Force. They fear losing responsibility for space and the nearly $8.5 billion of its budget that now goes for building and launching satellites, along with other space systems.

Vice President Mike Pence will renew the administration’s call for a space force in a speech at the Pentagon on Thursday. Deputy Defense Secretary Patrick Shanahan will lay out interim steps, including establishing a space command and a new joint agency for buying satellites, which the Pentagon plans to create by the end of the year.