Hundreds of workers at supermarket giant Asda are to stage a protest against new contracts they say will make them worse off.
Members of the GMB union will gather in Leeds on Wednesday to voice their opposition to the so-called Contract 6.
The GMB said workers face being dismissed in early November if they do not sign the contracts.
It said under the new contracts, workers will not be paid for any breaks and will have to work on bank holidays and weekends.
Justin Bowden, GMB national officer, said: "In the boardroom it may be all about the bottom line but out in the stores this is about real people's lives being pulled apart with often devastating consequences.
"This is about values and reasonableness and respect for hard-working staff from a billion-pound company.
"Telling dedicated workers to sign up no matter what the consequences to their personal lives or lose their jobs in the run-up to Christmas is truly shocking.
"Asda must get round the table, negotiate with GMB and stop Contract 6 ruining people's lives."
An Asda spokesman said: "The retail sector is undergoing significant change and it is important that we are able to keep pace with these changes.
"The overwhelming majority of our colleagues have signed onto the new contracts and while we appreciate that some of our colleagues find the changes more unsettling, we do not want any of them to leave.
"This contract is about increasing the take-home pay of more than 100,000 retail colleagues through an investment of more than £80 million and ensuring that everyone doing the same job is on the same terms and conditions."