WARSAW, Poland — ArianeGroup says this year will be decisive for the Ariane 6 rocket as the program is close to having all its propulsion qualified, including a full upper stage test this December.

Despite this progress, France’s supreme audit institution Cour des comptes has released a report in which it says that the Ariane 6 launcher is “at risk of not being sustainably competitive regarding its American competitor SpaceX.”

The French agency CNES provides a major share of Ariane 6 funding, giving France a vested interest in the launcher’s long-term success. France’s state auditor worries in its report that the vehicle could represent “but a transitory response to the challenge” posed by SpaceX’s “rise in power.” The Cour des comptes said the Ariane 6 “will need to evolve which will require decisions to be taken at European level.”

Asked about the Cour des comptes’ recommendations, Julien Watelet, the deputy head of media at ArianeGroup, said the company would not comment on the report, but that it was “keeping with the schedule, as planned.”

“We’re confident with the advancement of the program,” Watelet said.

To boost the European company’s competitiveness, the Cour des comptes calls on French authorities to enable the Ariane 6 to benefit from additional sources of funding. The report states that “the financial effort that is necessary to develop Ariane 6 should mobilize the totality of European funds,” replacing the European Space Agency’s current optional activity by a mandatory scheme that would require all member states to support the rocket program.

Cour des comptes’ report comes near the end of Ariane 6 launcher development. The rocket is now mostly complete, having started in 2014, and remains on track for a 2020 debut.

Arianespace, the sales arm of ArianeGroup, recently secured OneWeb as a customer for the inaugural Ariane 6 mission — an agreement that includes options for two additional Ariane 6 missions to support OneWeb’s deployment of 650 to 2,000 satellites.

Watelet said critical engine systems are already nearing finalization.

“The program is getting close to having all its propulsion qualified,” he said. “Vinci, the reignitable upper stage engine finished its qualification last October. Vulcain 2.1, the main stage cryogenic engine, is undergoing its second series of qualification tests, and will be qualified this year.”

Watelet said six Vulcain engines and five Vinci engines are already in production. The P120C strap-on booster, which doubles as the core booster for the Italy-led Vega C, had a second successful test in January, and will have a third test before the end of the year, he said.

“The combined tests between the launcher and the launchpad will start from January 2020 in the French Guiana,” Watelet said. “The whole year will be punctuated by many other significant milestones.”

The European Space Agency, ESA, and the German space agency DLR last month inaugurated a 50 million euro ($56.2 million) engine test facility in Lampoldshausen, Germany, intended to support Ariane 6 development.

Ariane 6 launcher stage assembly halls are now ready in France and Germany, along with all the other means of production in the European countries, Watelet said.

ESA oversees the procurement and architecture of the overall launch system, for which ArianeGroup says it is the prime contractor and design authority. Like Cour des comptes, ESA has described Ariane 6 as a rocket that will require continued evolution after its introduction.

Ariane 6 upgrades already in development include a lightweight carbon fiber upper stage and a low-cost engine called Prometheus that could support a reusable launcher.