RIVERSIDE, Calif. — The Justice Department said Monday that it might no longer need Apple’s assistance to help open an iPhone used by a gunman in the San Bernardino, California, rampage last year, leading to a postponement of a court hearing over the issue and temporarily sidestepping what has become a bitter clash with the world’s most valuable company.

In a new court filing, the government said that as of Sunday, an outside party had demonstrated a way for the FBI to possibly unlock the phone used by Syed Rizwan Farook, one of the San Bernardino attackers. The hearing in the contentious case — Apple has loudly opposed opening up the iPhone, citing privacy concerns and igniting a heated debate with the government — was originally scheduled for today.

“Testing is required to determine whether it is a viable method that will not compromise data on Farook’s iPhone,” the Justice Department wrote in the filing. “If the method is viable, it should eliminate the need for the assistance from Apple.” The Justice Department added that it would file a status report by April 5 on its progress on unlocking the iPhone.

Late Monday, Judge Sheri Pym, the federal magistrate judge in the U.S. District Court for the Central District of California who was set to hold the hearing, agreed to grant the Justice Department’s motion to postpone it.

The Justice Department’s move is a reprieve in the clash that has erupted between the U.S. government and Apple over how and when the authorities should use the troves of digital data collected and stored by tech companies. The two sides have traded barbs over the issue for weeks, ever since Apple received a court order last month demanding that the company comply with an order to weaken the security of the iPhone so law enforcement officials could gain access to the data in it.

The case has been viewed as a watershed moment in the debate over privacy and security. Apple had opposed the court order on the grounds that it would lead to a slippery slope of potentially having to open many iPhones, thus compromising the privacy of its many consumers. President Barack Obama said this month that law enforcement authorities must be able to legally collect information from smartphones and other electronic devices.

In a statement, Melanie Newsom, a spokeswoman for the Justice Department, said the FBI had continued to work on ways to gain access to the contents of the iPhone used by Farook, even as the fight between Apple and the government was unfolding.