His cautious backing for Sir Keir comes after Anas Sarwar, the Labour leader in Scotland, broke ranks to call for an immediate ceasefire.
Labour’s two most high profile mayors - Sadiq Khan in London and Andy Burnham in Manchester - have also clamoured for a change in policy.
Over the past week 13 shadow ministers have added their voices to demands that the party backs a truce without facing any sanction for rebelling.
They include Andy Slaughter, the shadow solicitor general, shadow safeguarding minister Jess Phillips, and Yasmin Qureshi, a shadow equalities minister.
Growing internal ruckus
Shabana Mahmood, the shadow justice secretary, also broke ranks by suggesting that Israel’s actions amounted to “collective punishment” of Palestinians.
Darren Jones, the shadow chief secretary to the Treasury, effectively confirmed on Monday that colleagues were free to oppose the official line without sanction.
He said: “It is perfectly right and proper for MPs who either one, hold personal views because of their personal connections to either Israel or Palestine or because they have personal political views.
“And secondly to that, all of us as elected Members of Parliament represent the people in our constituencies and that looks different in different parts of the country.
“It is right and proper that individual MPs represent their individual constituencies in Westminster, which is what they are doing. “
Downing Street opposed to ceasefire
Allies of Sir Keir have insisted he has no intention of changing his stance on a ceasefire, despite the growing internal ruckus.
They have said that the Labour leader wants to ensure that, as with the war in Ukraine, the UK is seen to be speaking with one voice.
That means he is only likely to change his position if the Government comes out and backs a truce in coordination with international partners like the US.
Downing Street is currently opposed to a ceasefire with Robert Halfon, an education minister, saying it is “not the answer”.
He said: “A ceasefire would allow Hamas to regroup, it doesn’t necessarily mean release of the hostages, there is no guarantee that Hamas would keep ceasefires.
“They haven’t kept ceasefires in the past. But that is different from having a humanitarian pause to allow aid to get through, and 30 trucks have gone through in recent days.
“Of course, we need as much aid to go and support the Palestinian people who are suffering because of Hamas. But we need to support them and make sure the aid gets to them, and isn’t taken away by Hamas.”