Retail union Usdaw is seeking a recognition agreement with Marks and Spencer to represent its employees.
The union has launched a national recruitment drive at M&S stores in a bid to boost membership figures and help encourage a formal agreement with the retailer.
Usdaw members are distributing leaflets to M&S employees across the UK.
General secretary John Hannett said: “This recruitment drive is being led by our existing members within M&S who are telling us that many of their colleagues would be interested in joining us.”
“M&S workers want an independent trade union and one that knows the retail sector inside out, so the more people who join the greater pressure there will be for M&S to talk to us about a formal recognition agreement.”
“Our members know our vast experience in the retail sector can help to protect their terms and conditions as M&S makes significant changes to the way it operates and we can work with the company to help make sure their recent revival continues.”