Dundee is to be the battleground for Labour clashes over the party’s position on Brexit.
Former Scottish Labour leader Kezia Dugdale has launched a grassroots campaign demanding the UK stays in the single market to protect jobs.
At least 10 local branches are issuing similar pleas to the leadership in motions for debate at the party’s conference at Caird Hall this weekend.
Jeremy Corbyn and Richard Leonard, the UK and Scottish leaders, insist the UK must leave the single market, the free trade area where people, goods, services and money can move unimpeded.
The launch of Scottish Labour for Single Market, which is co-led by former Shadow Scottish Secretary Ian Murray MP, will be seen as a challenge to Mr Leonard’s authority.
Ms Dugdale, who is now a backbench Labour MSP, said: “Jeremy Corbyn’s welcome decision to support a customs union puts clear blue water between us and the Tories.
“However, if we are to leave the EU, the least-worst option for limiting the damage caused by a Tory Brexit is to also remain in the single market.”
Ten of the 73 Scottish constituency Labour parties (CLPs) have already lodged motions in support of a soft Brexit.
The party’s conference arrangements committee will decide if the constituency motions will be put before delegates for debate.
Mr Corbyn faced criticism for trying to swerve debate on the single market at the UK conference in September.
The Labour leader has refused to commit to staying in the free trade area, which would mean unfettered EU immigration would continue, but said his party would seek a deal that “maintains the benefits of the single market”.
Lesley Laird, the Shadow Scottish Secretary and a Fife MP, told Sunday Politics Scotland: “When we leave the EU the current single market and the current customs union agreement falls away.
“The recognition is that we would need to negotiate new arrangements that would replicate the benefits of those.”
A Scottish Labour spokesman said there will be a Brexit debate at conference.
He added: “Scottish Labour will continue to seek a deal which retains the benefits of the single market and will not support a deal which does not.”
Mr Leonard insisted he is “quite relaxed” about the launch of the single market campaign, which is spearheaded by his predecessor.
“I’m a strong supporter of debate and dissent,” he told the Sunday Herald.