Lisa Nandy has said Labour’s amendment to the Scottish National party’s motion calling for an immediate ceasefire in Gaza is a moment to “lift our debate up” away from party politics and “speak with one voice”, ahead of what is likely to be a tense Commons vote on Wednesday. On Tuesday Labour explicitly called for a ceasefire in the region for the first time since fighting broke out in October, in an attempt to defuse a fresh crisis over Keir Starmer’s stance that had led to some of the party’s MPs rebelling in a vote over a ceasefire in November. “We hope that this is a moment where we can lift our debate up away from the party politics … and the whole house can speak with one voice alongside our international partners about the need for an immediate humanitarian ceasefire right now,” Nandy told BBC Radio 4’s Today programme. “The proposition that we’re putting before the house we believe can command the support of the whole house,” she said. In a carefully caveated 237-word amendment to the SNP motion calling for an immediate end to violence, Labour also calls for Israel not the invade to city of Rafah, for aid to be allowed to flow to Gaza and for the international community to work towards a two-state solution. It stresses that Israel cannot be expected to abide by a ceasefire if Hamas continues to threaten further violence. Labour’s amendment was followed by the government’s own, which also calls for a ceasefire once a long list of preconditions have been met, including that Hamas returns all hostages, that it cedes control in Gaza, that a new Palestinian government is formed and that there is a “credible pathway” to a two-state solution. The Commons speaker will choose on Wednesday morning which amendment to call. Nandy, the shadow minister for international development, said the problems with the SNP motion were twofold. Firstly, it did not lay out a “political horizon” that would make a ceasefire either achievable or sustainable, she said, and secondly, it needed to clarify that a ceasefire must be observed by Israel and Hamas. The shadow Scotland secretary, Ian Murray, issued a plea to the SNP Westminster leader, Stephen Flynn, to accept Labour’s “more balanced” amendment to the Gaza motion on Wednesday, warning that without this all attempts to gather cross-party support for a ceasefire were “doomed to fail” because of the government majority. Otherwise, he said: “We will sit here tonight after all the votes have been counted and everything will have failed but the government’s [amendment] because it’s a question of mathematics. “My plea to the SNP all of last week was if you truly want parliament to speak with one voice, let’s have a balanced motion that allows everyone to get behind it.” He said that if the SNP accepted the Labour amendment to its motion, which Murray said took a broader view, recognising Israel’s position and making proposals for a pathway forward from the conflict, “then we can spend our time this morning trying to persuade government members to get behind it and perhaps there’s a better chance of something being passed rather than us just being defeated by the government”. More than 28,000 Palestinians, mostly civilians, have been killed during Israel’s military campaign, according to the Palestinian health ministry, which was sparked by a Hamas attack on southern Israel on 7 October. In Rafah, more than 1 million people – at least half of the territory’s population – are seeking shelter without access to clean water or sanitation. In a joint statement earlier this month, Canada, New Zealand and Australia warned Israel against a ground invasion in Rafah and said an immediate humanitarian ceasefire was “urgently needed”. Nandy, who has visited the region twice in recent months, said: “It is a change in our position, it’s a significant step and not one that we’ve taken lightly.” She said that in November there had been every right to believe that a humanitarian pause was achievable. What had changed now, she said, was the collapse of the humanitarian situation in Gaza and the imminent ground invasion of Rafah. In November the SNP used the king’s speech debate to call for a vote on an immediate ceasefire in Gaza. At the time, Starmer’s whips urged MPs to back a Labour motion calling instead for a “cessation of fighting”, but dozens of MPs sided with the SNP. On Tuesday afternoon, Labour officials told the Guardian they believed they had successfully persuaded party rebels to vote for the amendment and abstain on the SNP motion. When asked by the Today programme whether members would abstain from voting for the SNP motion, Nandy replied: “That’s a question for the chief whip.” She said: “We are hopeful we will have the chance to put our proposition before the house and we believe that it offers the house a chance to speak with one clear voice alongside our five eyes partners and the international community.”