Public sector workers in Derby are trying to change government proposals to make people work until they are 65 before they can receive full pensions.
Teachers, prison officers and council staff will lobbying Derby North MP Bob Laxton and Erewash MP Liz Blackman at the city's Irish Centre on Saturday.
They say workers face having half their pension entitlement being cut.
Representatives from the Derby branch of the National Union of Teachers said it is causing alarm among some workers.
The leaders and members of 20 unions are attending the meeting to emphasis the strength of feeling on the issue.
With an aging population the government is thought to be looking at ways of limiting the cost of the state pension.