Sir Keir Starmer rejected any future election pact with Nicola Sturgeon’s SNP to push Boris Johnson from power.
The Labour leader said his party would refuse to enter a coalition with the SNP due to their pro-independence stance.
He also slammed the Tories for their “reckless” attitude to Scotland and claimed they “don’t care” what happens north of the border.
Recent polling has indicated Labour could become the UK’s biggest party after the next election – but they may still fall short of a majority.
Ms Sturgeon’s SNP could potentially hold the balance of power at Westminster and is committed to holding another independence referendum.
But in a set-piece speech in Birmingham on Tuesday Sir Keir said he was “very clear” he would not work with the nationalists.
‘No deal with the SNP’
Speaking earlier today, the Labour chief said: “As I’ve said before, no deal with the SNP going into an election, no deal with the SNP coming out of an election, I’m very clear about that.”
Sir Keir outlined his vision for Britain if he manages to take power and said he believes the UK is “better together”.
He added: “I believe that these values – security, prosperity and respect – unite the whole of the United Kingdom.
I believe in our union of nations.
– Sir Keir Starmer
“The UK is a unique construct of four distinct national identities. It’s complex, and it can easily be exploited for political gain, as we have seen.
“A reckless government in Westminster that doesn’t seem to care about what happens in Scotland erodes people’s faith in our common bond.
“But I believe in our union of nations. I believe we are better together than any of us would be apart.
“I believe each nation can speak with a progressive voice.
“But we do need a new and durable constitutional settlement, which is why I’m delighted that Gordon Brown’s commission on the future of the UK will chart a new course for our union of nations.”
Sir Keir added that Boris Johnson had been “too weak” to introduce new Covid restrictions in England amid recent surges in Omicron cases.
Labour previously backed the Prime Minister’s Plan B approach to the virus despite a major rebellion from backbench Tory MPs.
A senior SNP MP accused Sir Keir of “hot air” after his speech earlier today and said his party would not offer Labour a coalition deal anyway.
John Nicolson wrote: “No one, of course, is talking about a Labour SNP coalition. So Keir Starmer is “rejecting” something he’ll never be offered. All hot air.”