KEIR Starmer is set to promise that Labour will never make a deal with the SNP in Westminster to spike Tory attacks lines on a “coalition of chaos” that would target English voters, according to reports.

The Labour party leader will vow that his party would rather go into a minority government than work with the SNP as he ramps up his pledge to prevent indyref2, which will be a key element of his summer campaigning, reports The Guardian.

It is likely that Starmer will offer a procedural guarantee against a deal with the SNP, and include a motion to the party’s conference. According to sources for the paper, the commitment would demonstrate party members were supportive of the move.

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Senior figures around the Labour party leader have urged him to make a strong case in support of the strategy to voters, especially in England.

“We must be louder making this argument,” one strategist said.

Strategists say this would help dispel the Tory line before it is established, drawing comparisons to how Starmer distanced himself from the anti-semitism row that engulfed the party during Jeremy Corbyn’s tenure as leader.

Anas Sarwar is expected to reflect this line in his own speech to the Fabian Society on Monday which will be followed by meetings with the shadow cabinet and MPs to confirm the party’s strategy.

“Keir does not take any persuading to be hardline on this stuff,” one senior ally said. “He implicitly understands what a threat it is not just to the success for the party in Scotland but also how effective those attacks can be in England.”

It is expected that the Tories south of the Border will make arguments that Labour cannot form a majority government based on current polling and would have to look to the SNP for support.

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Earlier this week, Matt Hancock, who is rumoured to be making a play to be the new Conservative party chair, attempted to make the argument while writing in the Daily Mail.

He said: “Almost the only viable alternative to a Conservative government is a coalition between Sir Keir and Nicola Sturgeon’s separatist SNP … the risk of a grubby coalition deal that sells the Union down the river.”

And there are concerns among Labour strategists that their own supporters could come round to the idea of a progressive alliance with the SNP.

“There are parts of the party who still think we are on the same side,” one senior Scottish Labour source said.

In the run up to the local council elections Sarwar vetoed any coalitions with the SNP, forcing them to make deals with other parties. This led them to lose power in Aberdeen to an SNP-LibDem coalition but they formed minority administrations elsewhere, including in Edinburgh, East Renfrewshire, and Fife.

However, these deals have caused some internal tensions as last week two Labour councillors were suspended after refusing to vote for a minority deal that gave two Tories committee posts in return.

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The reports of a potential veto on any deal with the SNP has sparked discussion on Twitter with commentators comparing the moral and political justifications for the strategy.

Political journalist Ian Dunt said: "Morally, this is wrong. The SNP and Greens have a mandate for another referendum. But politically, it is surely the correct approach."

Dunt's comment prompted a reply from Nicola Sturgeon who voiced frustration as she said that the political interests of the rest of the UK often take precedence over what is best for Scotland. 

She wrote: "The problem in a nutshell. When morally right move for [Scotland] clashes with politically expedient for rUK, latter always take precedence. We should be political equals and work together as Indy countries on that basis. (This not directed @IanDunt btw - I think he’s great)