Labour's leadership candidates have been challenged on how they will tackle both the rise of the SNP in Scotland, and Tory tactics to use the nationalists against the party in England.
The four leadership hopefuls were taking part in a hustings event in Glasgow as the contest to take over at the Labour helm continues.
The party was almost wiped out north of the border at the general election in May, losing all but one seat as the SNP made sweeping gains.
Frontrunner Andy Burnham told the audience at the City Halls that the party must tackle nationalism, which is "on the march all over the UK".
"We have got to take nationalism on across the UK because it is an ugly political philosophy in the end," he said. "It is politics based on borders, not people."
Mr Burnham said Labour must promote "solidarity not separation" by convincing people that the interests of those in the north of England are the same as those in the west of Scotland.
He added: "In recent years our party has become more and more and more London-centric, more and more and more out of touch with people. This party is now out of touch with millions of people and we have got to put that right."
Some in the party have argued that Labour suffered in England as a result of a Conservative election strategy which suggested that former leader Ed Miliband would do a deal with the SNP.
Liz Kendall told the audience that she would be the leader "the Tories fear".
"The question was how do we stop the Tories using the SNP against us in England," she said. "The reason why they could do it is because we were too weak in England.
"We wanted people to trust us with the economy and their taxes, and we didn't have a vision of a better life that everybody could feel part of."
She added: "The only way to rebuild trust with the people of Scotland is to show them that we are the party for the people of Scotland."
"I will make this promise to you – as leader of the Labour Party, I will stand shoulder to shoulder with you month in, year out so that we can rebuild trust and win back support. Because if we are strong across the country and here, that's how you can stop the Tories using the SNP."
Shadow home secretary Yvette Cooper said Labour had suffered in Scotland as a result of the independence referendum, but needed to be "prepared to take the Tories on and take the SNP on, not to give in to their myths and to hold both of them to account".
She said neither party was progressive in their policies. "Let's call them out on this – they are not progressive in the SNP, they are certainly not progressive in the Tories," she said.
"We as the Labour Party have got to have confidence not to swallow all of their myths ... but stand up for our values, our politics, our ideas - that is how we can win elections."
Left-winger Jeremy Corbyn, whose leadership bid has been boosted by trade union support, said: "The SNP are very good at presenting themselves as the anti-austerity party."
But he argued that SNP plans for full fiscal autonomy would have resulted in "turbo-max austerity" in Scotland today.
"We need to be campaigning for fair funding for Scotland, which means perhaps formulating it around the needs, the poverty, the desperation, that some of the people of Scotland face," he said.
"This city contains some of the poorest people in the whole of the UK ... these things have to be addressed, and they have to be addressed by us.
"Labour has got to be the party that is standing up for the poorest people wherever they are."