Thousands of people are expected to join a huge march and rally in protest at the decision to end car production at one of Vauxhall's UK plants.
Workers involved in the campaign to save the Rover plant at Longbridge, Birmingham last year are among those taking part in the protest in Luton.
Unions have launched a campaign to reverse the decision, which will include a ballot for industrial action and a Europe-wide day of action later this month.
Production of the Vauxhall Vectra is due to end in a year's time, with the loss of 2,000 jobs at the plant - and thousands more in associated areas of the car industry.
Tony Woodley, national officer of the Transport and General Workers Union, says that a series of mass meetings earlier this week in Luton, and at Vauxhall's other site in Ellesmere Port, sent a strong message of support for the campaign.
He commented: "The feeling is that the decision must be fought, and fought hard."
Roger Lyons, general secretary of the Manufacturing Science and Finance union added: "The demonstration will show the anger of the workforce and the local community towards General Motors' decision to close the profitable Luton plant."
He said GM had made £1 billion profit from Vauxhall workers in the last 10 years, which worked out at £100,000 per worker.
Sir Ken Jackson, general secretary of the Amalgamated Engineering and Electrical Union said: "It is unacceptable for Vauxhall to close a British plant to solve a European problem. Vauxhall is profitable and productive and we believe there is a strong case for keeping Luton open."
Vauxhall has blamed the closure decision on huge over capacity in the car market and on heavy European losses.