Keir Starmer is facing growing pressure to support a Labour amendment backing a ceasefire in Gaza to head off the possibility of his own MPs voting for an SNP motion that will call for an immediate halt to the fighting. A meeting of Labour’s parliamentary party (PLP) on Monday was described as “a bin fire” by one MP, with a separate campaign by pro-ceasefire Labour members launching on Tuesday. “Everyone is begging [Starmer] to do it,” they said after the highly charged meeting late on Monday night, where the shadow foreign secretary, David Lammy, attempted to hold the party line. When the king’s speech debate comes to an end on Wednesday, it is likely there will be a vote on the SNP’s amendment, which calls on the government to “join with the international community in urgently pressing all parties to agree to an immediate ceasefire”. Starmer is facing a rebellion by as many as a dozen shadow ministers, who sources say are ready to resign rather than vote against calling for a ceasefire in the Middle East, which Starmer has refused to back. Pressed on whether Labour MPs would be allowed a free vote, the shadow chancellor, Rachel Reeves, said on Tuesday that MPs “didn’t know” in terms of what the speaker would pick in terms of amendments, and “would address that” tomorrow. “There [are] a number of amendments down at the moment we don’t know what the vote will be on,” she told BBC Radio 4’s Today programme. Pressed on what would need to happen in terms of the death toll before Labour backed a ceasefire, she said: “The numbers are already too high. Far too many innocent people in Israel and Gaza have lost their lives.” “The way to stop this killing and the way to save lives is for the international community to come together and put pressure both on Hamas to release the hostages,” she said, adding that the international community also had to put pressure on the Israeli government to show “more restraint”. A campaign to put pressure on the Labour leadership to back a ceasefire will meanwhile also be launched on Tuesday by Mish Rahman, a member of Labour’s national executive committee (NEC) from the West Midlands. “We have seen leaders, who claim to represent us, rule out the commitment to a ceasefire which would put an end to the terrible violence, open up the opportunity for talks and a move towards a peaceful solution,” Rahman said on a new website, which is collecting signatures to support the Labour for a Ceasefire Now campaign. “How many more children must die before our party advocates for peace? It is time for change. It is time to end mealy mouthed politics. It is time for political triangulation to change. It is now that there is time for honesty – we need a politics of peace.” Before the end of the king’s speech debate, a script seen last week by the Guardian instructed Labour party whips to be firm with frontbenchers, and “point out that if Labour was in government they would have to vote against”. Starmer has said he understands the “emotions” behind the ceasefire calls of some in the party.