Sir Keir Starmer is braced for a mutiny this evening, with as many as 50 of his own MPs said to be considering rebelling and voting for the SNP's amendment calling for an immediate ceasefire.
Some MPs on the frontbenches of the party are also said to be prepping resignation letters - but others are likely to be sacked by the leadership if they break with the party line.
The SNP last week tabled an amendment to the King's Speech calling for an immediate ceasefire in the war. The vote will take place this evening, after being selected by the Speaker.
GB News understands there could be as many as ten frontbenchers considering backing the amendment, meaning they would either be forced to quit or be sacked.
Labour MPs are under a three-line whip not to vote in the SNP's amendment.
A party spokesperson yesterday said: "We're not going to be engaging with the party political game playing by the SNP in parliament."
They added today: “This is a whipped vote and every MP knows what the consequence of that means.”
But GB News understands MPs are not likely to have the whip removed if they break the party line on this issue.
Shadow Home Office Minister Naz Shah became the first MP to publicly confirm she will defy the Labour whip and vote for a ceasefire this evening.
She said: "Despite all the risk to our personal positions we must do what is right".
A total of 19 shadow ministers have publicly backed a ceasefire in Israel and Gaza, as well as 70 backbenchers, breaking with Starmer's stance of calling for "humanitarian pauses".
He has warned that calling for a ceasefire would serve to "embolden Hamas".
Sources told the House Magazine that more than 50 MPs could vote with the SNP this evening.
Former frontbencher Rosena Allin-Khan, whose name is on the amendment, issued a statement this afternoon confirming her stance on the issue.
Calling for a ceasefire, she said: "I cannot stand by while collective punishment is inflicted on so many civilians".
Labour has also tabled its own amendment calling for "humanitarian pauses", in what is seen as an attempt to promote party unity.
A spokesperson said: "Labour's amendment reaffirms the position set out in Keir Starmer's Chatham House speech and reflects our concerns about what we've seen on the ground in the last fortnight which includes the lack of hostage release, the insufficient amount of aid and utilities getting in and being distributed, the scale of civilian casualties in Gaza and the amount of violence on the West Bank."
The Chatham House speech saw Starmer dismiss calls for a ceasefire, saying: "I do not believe that is the correct position now, for two reasons.
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The Chatham House speech saw Starmer dismiss calls for a ceasefire, saying: "I do not believe that is the correct position now, for two reasons
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"One, because a ceasefire always freezes any conflict in the state where it currently lies."
Speaking about the SNP's amendment, a source told the Telegraph: "Support for this motion is not compatible with serving on the front bench.
"There will be absolutely no dilution in the position not to back a ceasefire."
