The proposal, released as a discussion draft last month, may not be formally introduced this year because of strong opposition, according to a Reuters report.
The draft bill, pushed by Senators Richard Burr and Dianne Feinstein, would allow judges to order tech companies to comply with requests from the FBI and other law enforcement agencies to help them defeat security measures and break into devices.
"All persons receiving an authorized judicial order for information or data must provide, in a timely manner, responsive, intelligible information or data, or appropriate technical assistance," the draft bill said.
Spokespeople for Burr, a North Carolina Republican and chairman of the Senate Intelligence Committee, and Feinstein, a California Democrat, didn't immediately respond to requests for comment on the future of the proposal.
The proposal received a cool reception from President Barack Obama's administration, despite a long-running push by FBI Director James Comey to allow law enforcement agencies access to devices protected by encryption and other security measures. The FBI and parent agency the Department of Justice have gone to court to force Apple to help them defeat encryption on iPhones in a handful of recent criminal cases.
The FBI asked a California judge to order Apple to assist it with unlocking an iPhone used by a mass shooter in San Bernardino, California, in December, but the agency later backed off after it said it found an alternative method.
Several digital rights groups have also opposed the encryption proposal. Since mid-April, more than 70,000 people have opposed the draft bill by signing a petition from progressive activist group CREDO Action.