Cleaning staff working for a government contractor are preparing to ballot for industrial action over pay and conditions.
The Transport and General Workers Union (T&G) says contract cleaners employed by Mitie Managed Services in government buildings across the region are paid only the minimum wage and that is not enough.
But Mitie says its cleaners are all paid the prevailing commercial rate for cleaners in the area.
Hundreds of helium balloons with the slogan "£5 Now" will be released outside a government office in Birkenhead by the union as part of the campaign.
Mick Cashman, T&G regional industrial organiser, said unless Mitie and the government act to address the problem they will face a concerted campaign of protest and industrial action.
"Our members are determined to win this claim for a fair deal for cleaners," he said.
"Contract cleaners are sick of poverty pay and poor conditions
"Mitie and the government should be ashamed that cleaners are employed on these conditions in their buildings."
In addition to the pay claim, the union says many are also only being allowed 12 days holiday a year plus bank holidays.
The T&G wants workers to be paid a minimum of £5 per hour, with 21 days holiday, plus bank holidays.