The Labour leader would become prime minister with a 212-seat majority if an election were held tomorrow, according to a Survation poll on behalf of the UK Spirits Alliance.
The survey, based on new constituency boundaries taking effect at the next election, is the first of its kind since Hamas launched a wave of terror attacks on Israel on 7 October.
In the month since, Sir Keir’s party has been plagued by infighting over whether to call for a ceasefire as the civilian death toll grows in Gaza.
The Labour leader has defied pressure to call for an end to Israel’s assault, warning that to do so would solely benefit Hamas.
He has instead called for “humanitarian pauses” to allow aid into the besieged Strip, in line with the UK and US governments.
But several frontbenchers have rejected the principle of “collective responsibility”, breaking the party line and backing a ceasefire. Last week Imran Hussain, the MP for Bradford East, announced he was quitting his role as shadow minister for the new deal for working people, to be able to “strongly advocate” for a ceasefire.
Almost 50 Labour councillors have quit and hundreds of local representatives oppose the leadership’s stance.
Despite the weeks of infighting dominating media coverage of Labour, the new poll suggests the party could secure 431 seats, compared to the Conservatives on 156.
In his 1997 victory, Sir Tony Blair won 418 seats, compared with Sir John Major’s Tories on 165, securing a 179-seat majority.
The Survation poll, reported by The Sunday Times, suggests nine cabinet ministers would lose their seats, including former leadership contender Penny Mordaunt, seen by many as a major contender to replace Rishi Sunak.
Other major scalps that are expected include defence secretary Grant Shapps, transport secretary Mark Harper, work and pensions secretary Mel Stride and justice secretary Alex Chalk.
A separate Opinium poll this weekend revealed Labour’s lead over the Conservatives has increased to 17 points, up from 15 a fortnight ago.
Labour now has 43 per cent of the vote share, while the Conservatives are on 26 per cent.
Opinium said Labour and Sir Keir have taken some “big hits” in terms of public perception over the conflict in Gaza, but the Conservatives have “let them off the hook”.
James Crouch, Opinium’s head of policy and public affairs, said: “The government seems to have let Labour off the hook on what could have been a very difficult week for the opposition.
“Labour’s response to the conflict in the Middle East has made the party look less united, and Starmer look much weaker than before. However, by the end of the week the news had moved on to Conservative divisions and indecision, leaving the door open to a 17-point Labour lead in the polls.”