The BBC understands mediators have spoken with Izz al-Din al-Haddad, who leads Hamas's military wing in Gaza, and that he does not accept a new US-backed ceasefire framework. The proposal, drawn up by the US administration and already agreed by Israel, calls for Hamas to disarm and to have no future governing role in Gaza.
Those involved in the discussions say al-Haddad regards the package as a blueprint aimed at ending Hamas whether the group cooperates or not, and is therefore resolved to continue fighting. A key sticking point is the demand that all hostages be released within the first 72 hours of any ceasefire, a condition many in Hamas find unacceptable because it would surrender their main leverage.
Negotiators say there are believed to be 48 hostages still held, with only about 20 thought to be alive. Some members of Hamas's political leadership based in Qatar are reported to be open to the plan with amendments, but their ability to influence events in Gaza is limited because they do not control the hostages themselves.
Another factor undermining confidence in the proposal is mistrust of Israel. Hamas figures point to a recent air strike in Doha that targeted senior members of the group's leadership as evidence Israel might not adhere to commitments made as part of any deal.
Parts of the proposal envision deployment by the US and Arab states of what it describes as "a temporary International Stabilisation Force" in Gaza. Some within Hamas view such a force as tantamount to a new occupation. The Trump administration has also circulated a map showing phased Israeli withdrawals that would leave what it calls a "security buffer zone" along Gaza's borders with Egypt and Israel; how that zone would be governed has not been made clear and could also prove contentious.
Since endorsing the plan, Israeli Prime Minister Benjamin Netanyahu has signalled reservations about several aspects. In a video posted on social media he said Israeli forces would be able to remain in parts of Gaza and that Israel would "forcibly resist" a Palestinian state.
The US text, by contrast, specifies that Israeli forces would pull back and describes the withdrawal as being complete "save for a security perimeter presence that will remain until Gaza is properly secure from any resurgent terror threat". It also states there may be a "credible pathway to Palestinian self-determination and statehood" once the plan is implemented.
Israel launched a military campaign in Gaza after the Hamas-led attack on southern Israel on 7 October 2023, in which about 1,200 people were killed and 251 others taken hostage. Since then, Gaza's Hamas-run health ministry reports at least 66,225 people have died in Israeli strikes.