Vauxhall car workers are preparing to vote on whether to strike in protest at job losses.
Union secretaries will address meetings in Luton and Ellesmere Port, over the next few days urging support for industrial action.
The ballots are part of a union campaign aimed at reversing the decision to end car production at Luton next year with the loss of 2,000 jobs.
Workers at Vauxhall's parent firm General Motors held a day of action last week in protest at the job losses.
The ballot result will be announced next month.