Nvidia’s prospects of getting regulatory approval for its $55 billion acquisition of microchip designer Arm Holdings from SoftBank are looking increasingly imperiled, according to two people involved in the process.

The deal, which would reshape the global chip industry, has been stuck in regulatory reviews for more than a year. Recent actions taken by officials in Europe have signaled to the companies and to powerful opponents of the deal that an antitrust review won’t be done soon. At the same time, U.S. antitrust regulators have indicated to the same opponents that they are considering whether to try to block it in court, one of these people said. Regulators in China, where an antitrust review of the deal hasn’t even begun, remain a major obstacle as well.

That suggests the companies will have to wait at least another full year to have any chance of getting approval—far beyond the timelines they have discussed publicly, these people said.