Trade union Unite has urged Mandelson, who is visiting the workforce at the Luton plant today, to save the thousands of staff at the vehicle manufacturer from redundancy.
Len McClusky, assistant general secretary for Unite, said: "Workers at the Luton plant are extremely worried about their futures and they will be pleased a Government minister is coming to see for himself the pride this workforce has in the product it makes."
The call comes as GM Europe continues to seek an investor for Vauxhall and Canadian components company Magna has emerged as a possible buyer.
Mandelson said: "I want workers to know we are doing everything possible to secure a long-term commercial future for Vauxhall. My officials and I are in constant contact with the US and German governments, GM US and GM Europe and others to ensure Britain's interests are fully represented. We also continue to have detailed discussions with Magna and other interested parties."
Lord Mandelson promises action to secure Vauxhall's long-term future and save jobs
Business secretary Lord Mandelson has pledged to do "everything possible" to secure the long-term commercial future of Vauxhall, where 1,450 UK jobs are at risk.