US Secretary of State Antony Blinken has said that if a ceasefire plan backed by the US and UN does not progress, Hamas will be to blame.
Mr Blinken reiterated his call for Hamas to accept the plan as outlined by President Biden 11 days ago.
He said the onus was on "one guy" hiding "ten storeys underground in Gaza" to make the casting vote, referring to Hamas leader Yahya Sinwar.
Mr Blinken said Israeli Prime Minister Benjamin Netanyahu had "reaffirmed his commitment" to the proposal when they held talks in Jerusalem on Monday.
Mr Netanyahu has not publicly endorsed what Mr Biden outlined nor said whether it matches an Israeli proposal on which Mr Biden's statement was based.
Mr Blinken described as a "hopeful sign" Hamas's response to a resolution passed by the UN Security Council on Monday supporting what Mr Biden had announced.
The resolution noted that Israel had accepted what Mr Biden had presented and called on Hamas to do so as well.
Hamas issued a statement on Tuesday welcoming "what was included" in the resolution.
But Mr Blinken said Hamas's response was not conclusive, adding that that "what counts" is what is said by the Hamas leadership in Gaza, "and that's what we don't have".
If the proposal did not proceed then it was “on them”, he said.
After months of stuttering ceasefire talks behind closed doors, Mr Biden publicly announced last month what he said was an Israeli "roadmap to an enduring ceasefire and the release of all hostages" which he then went on to outline.
The actual Israeli proposal - reportedly lengthier than the summary presented by Mr Biden - has not been made public and it is unclear whether it varies from what the president conveyed.
The Israeli proposal was agreed upon by Israel’s three-man war cabinet and has not been divulged to the wider government. Some far-right ministers have already made clear they oppose it. Mr Netanyahu has not said directly whether he supports the plan as laid out by President Biden.
The US said the Israeli proposal had been presented to Hamas by mediator Qatar earlier that week.
