Hamas made a pretty significant adjustment in its position over a potential hostage release deal with Israel, a senior U.S. administration official said on Thursday, expressing hope that it would lead to a pact that would be a step to a permanent cease-fire.

"We've had a breakthrough," the official told reporters on a conference call, adding there were still outstanding issues related to implementation of the agreement and that a deal was not expected to be closed in a period of days.

Israeli Prime Minister Benjamin Netanyahu told President Joe Biden on Thursday he has decided to send a delegation to resume stalled negotiations on a hostage release deal with Hamas.

The U.S. official said Biden was encouraged that Netanyahu was authorizing his team to join the talks.

"We do believe there is a pretty significant opening here, and we welcome the prime minister's readiness to try to seize that opening by empowering his negotiating team to engage directly in Doha here over the coming days," the official said.