President Trump is reportedly planning to request an end to funding for the International Space Station (ISS) by 2025, a move that would be a major hurdle to expanding space exploration efforts.

The president's official budget for fiscal year 2019 is scheduled to be released next month, but a draft proposal, seen by The Verge, would call for U.S. support for the program, which has been in place for more than 20 years, to end.

NASA contributes between $3 billion and $4 billion to the International Space Station every year, according to The Verge. It is key as a destination for American astronauts who currently have no alternative destinations in orbit.

According to The Verge, commercial companies like SpaceX and Boeing have said they would likely not be able build orbiting modules by the time funding for the ISS runs out in 2024.

A NASA spokesperson declined to comment on the budget draft, but noted the program's importance to human space travel.

"NASA and the International Space Station partnership is committed to full scientific and technical research on the orbiting laboratory, as it is the foundation on which we will extend human presence deeper into space," the spokesperson said.

The move lines up with Trump's efforts to move NASA funding away from international efforts and toward other space exploration projects, like building vehicles to explore deep space and returning American astronauts to the Moon.

Last year, Trump signed an authorization act that directed NASA to find a way for the ISS to be less reliant on NASA funding.

An Obama-era action extended the NASA-ISS partnership until 2024, but players in the commercial space industry have pushed for funding for the ISS to be continued beyond that deadline, according to The Verge.