Last month's Barker Report on planning recommended that the test, which forces developers to prove a scheme is required, should go. Kate Barker, the author, said investing developers were better placed than local authorities to decide if a new store were needed.
But the ACS said it feared abolishing the test would mean a further increase in the number of supermarkets and a major increase in the dominance of the big four, harming small independents.
It has contacted 200 MPs to voice concerns. "The needs test is a vital part of national planning policy that promotes sustainable retail development," said James Lowman, ACS chief executive. "We are asking MPs to support our campaign to maintain the test. We believe they will agree it should be local authorities and people that decide if an area needs a supermarket."