Two far-right Israeli ministers have threatened to quit and collapse the governing coalition if Prime Minister Benjamin Netanyahu agrees to a Gaza ceasefire proposal unveiled by US President Joe Biden on Friday.
Finance Minister Bezalel Smotrich and National Security Minister Itamar Ben-Gvir said they were opposed to striking any deal before Hamas was destroyed.
Opposition leader Yair Lapid has pledged to back the government if Mr Netanyahu supported the plan.
The prime minister himself insisted there would be no permanent truce until Hamas's military and governing capabilities were destroyed and all hostages released.
However, before the threats of resignation were issued, one of Mr Netanyahu's advisers told the Sunday Times the plan was something "we agreed to" and emphasised Israel was not rejecting it, even if if it was not considered a "good deal".
Mr Biden's three-part proposal would begin with a six-week ceasefire in which the Israel Defense Forces (IDF) would withdraw from populated areas of Gaza. The deal would eventually lead to the release of all hostages, a permanent "cessation of hostilities" and a major reconstruction plan for Gaza.
But in a post on social media on Saturday, Mr Smotrich said he told Mr Netanyahu he would "not be part of a government that agrees to the proposed outline and ends the war without destroying Hamas and bringing back all the hostages".
Echoing his words, Mr Ben-Gvir said "the deal.. means the end of the war and the abandonment of the goal to destroy Hamas. This is a reckless deal, which constitutes a victory for terrorism and a security threat to the State of Israel".
He vowed to "dissolve the government" rather than agree to the proposal.
Mr Netanyahu's right-wing coalition holds a slim majority in parliament, relying on a host of factions, including Mr Ben-Gvir's Otzma Yehudit (Jewish Power) party - who hold six seats - and Mr Smotrich's Religious Zionism party - who hold seven seats - to maintain power.
But Yair Lapid, one of Israel's most influential opposition politicians, was quick to offer his backing to the embattled prime minister. His Yesh Atid (There is a future) party hold 24 seats.
He said the prime minister "has our safety net for a hostage deal if Ben-Gvir and Smotrich leave the government".
Before the intervention of Mr Netanyahu's government partners, a senior foreign policy adviser said many details of the plan needed to be worked out and there would be no permanent ceasefire "until all our objectives are met".
But, in an interview with the Sunday Times newspaper, Ophir Falk also said Mr Biden's plan was a "deal we agreed to - it’s not a good deal but we dearly want the hostages released, all of them".
The row came as tens of thousands of people rallied in Tel Aviv, calling on the Israeli government to accept Mr Biden's proposed plan.
Many demonstrators also demanded Mr Netanyahu's resignation and some told reporters they feared the prime minister could torpedo the proposal.
A group campaigning to bring home Israeli hostages captured by Hamas has warned that such a move would endanger the lives of those held in Gaza.
Scuffles broke out between protesters and police, who used mounted officers and water cannon to disperse the crowds. Some demonstrators were reportedly detained.
Protests have become a fixture in Tel Aviv in recent months, as families of hostages and other anti-government campaigners have held rallies calling for a hostage deal - as well as for Mr Netanyahu to step down or call an election.
In a joint statement on Saturday, mediators from Egypt, Qatar and the US urged both Israel and Hamas to "finalise" Mr Biden's proposed deal.
Officials said that "as mediators in the ongoing discussions to secure a ceasefire in Gaza and the release of hostages and detainees", they "call on both Hamas and Israel to finalise the agreement embodying the principles outlined by President Joe Biden".
UK Prime Minister Rishi Sunak also offered his backing to the plan, telling reporters that his government could "flood Gaza with far more aid" if Hamas accepts the ceasefire plan.
Earlier, a senior Hamas politician told the OceanNewsUK it "will go for this deal" if Israel does.
In a statement after Mr Biden unveiled the plan, Mr Netanyahu's office insisted Israel's "conditions for ending the war have not changed".
It listed these as "the destruction of Hamas military and governing capabilities, the freeing of all hostages and ensuring that Gaza no longer poses a threat to Israel".
The statement added Israel would "continue to insist these conditions are met" before agreeing to a permanent ceasefire.
However, the comments seemed to be vague enough for Mr Netanyahu to be able to claim that his objectives had been achieved.
Mr Netanyahu's office did not mention “total victory” - which he has repeatedly highlighted as a key aim for the war in Gaza.
This omission may allow the prime minister to reject criticism that the deal offers major concessions to Hamas.
On Sunday, Israeli President Isaac Herzog said on social media that he would give Mr Netanyahu's government his "full support for a deal which will see the release of the hostages".
"It is our inherent obligation to bring them home within the framework of a deal that preserves the security interests of the State of Israel," he said
Elsewhere, fighting continued in Rafah on Saturday, with reports of Israeli air strikes on Gaza's southern city on Egypt's border.
Shelling and gunfire were also reported in Gaza City, in the north of the Palestinian territory.
More than 36,000 people have been killed in Gaza since the start of the conflict, according to the Hamas-run health ministry.
The war began on 7 October 2023 when Hamas gunmen launched an unprecedented attack on Israel, killing about 1,200 people and taking 252 back to Gaza as hostages.
