High-level cease-fire talks appeared to be gaining momentum on Monday as Arab and American mediators pressed for an agreement to halt the fighting in Gaza and release hostages held by Hamas before President-elect Donald J. Trump assumes office on Jan. 20.

It was still unclear whether the parties had reached resolution on central disputes that have proved insurmountable in previous rounds of negotiations, but officials briefed on the talks have expressed cautious optimism in recent days about the possibility of concluding a deal.

For months, repeated rounds of talks have seen hopes rise only to be dashed days later, with both Israel and Hamas blaming the other for the impasse.

If a deal is achieved, it would bring some respite to Palestinians in Gaza, who have endured miserable conditions in displacement camps and relentless bombardments by Israel, and the families of hostages taken from Israel, who have suffered for months wondering about the fate of their loved ones.

  • The lead mediators in the talks are Qatar and Egypt, shuttling messages between Israel and Hamas. The Qatari prime minister, Sheikh Mohammed bin Abdulrahman bin Jassim Al-Thani, and the director of Egypt’s General Intelligence Service, Maj. Gen. Hassan Rashad, have been the top officials representing their countries in the negotiations.

  • David Barnea, the chief of Israel’s foreign intelligence service, Mossad, is one of Israel’s main negotiators, alongside Ronen Bar, the head of the Shin Bet, a domestic security service, and Maj. Gen. Nitzan Alon of the Israeli military. Ophir Falk, a foreign policy adviser to Prime Minister Benjamin Netanyahu, has also participated in important meetings related to the negotiations.

  • Khalil al-Hayya, a senior Hamas official based in Doha, is the militant group’s chief negotiator and has interfaced with Qatari and Egyptian officials about the details of a possible agreement.

  • The United States has used its leverage to encourage Israel and Hamas to sign on to a deal. Bill Burns, the C.I.A. director, and Brett McGurk, a senior White House official, have crisscrossed the Middle East, pressing for a breakthrough in the talks. Steve Witkoff, Mr. Trump’s Middle East envoy, has also made trips to Qatar and Israel, meeting with top officials there.

Israeli officials hope to secure the release of at least some of the roughly 100 hostages who have been held in Gaza since the Hamas-led attack on southern Israel on Oct. 7, 2023, that ignited the ensuing war in the territory.

Hamas leaders want to achieve an end to the war in Gaza, which has severely weakened the group’s armed wing and government, led to the displacement of nearly two million people, and reduced cities to rubble. Hamas officials have also said they are seeking a complete Israeli withdrawal from Gaza, the return of displaced people in the south of the enclave to the north, and the entry of materials for reconstruction.

  • A major obstacle to the success of the talks has been the permanency of a cease-fire. While Hamas has demanded a comprehensive end to the war, Mr. Netanyahu has said he wants a “partial” deal that will allow Israel to resume the war after freeing hostages.

  • Israel has been demanding vague language in the text of an agreement that leaves room for a resumption of fighting at some point, according to a Palestinian familiar with the matter and two Israeli officials. Mr. Netanyahu has feared that his right-wing coalition partners could take down his government and jeopardize his political future if he agrees to a deal that ends the war in Gaza, analysts say.

  • Hamas has not suggested it would be willing to compromise on its demand to end the war. Last week, Osama Hamdan, a senior Hamas official, told a gathering in Algeria that there must be “an absolute end to the aggression.”