The conservative union that undercut the pay and conditions of more than 250,000 workers in a series of substandard wage deals is seeking to "come in from the cold" by rejoining Victoria's peak union body.

But the move by the Shop, Distributive & Allied Employees Association (SDA) has been met with heated opposition from one rival union in particular, and renewed criticism of its industrial practices.

SDA state secretary Michael Donovan. Credit:SDA

The SDA – the "shoppies" – left the Victorian Trades Hall Council in the early 1990s complaining about its pro-land rights (Mabo) position and political direction at that time.

It is renowned as the last bastion of Catholic conservatism in the labour movement, for its key role in the Labor split of the 1950s that kept the ALP from power in Canberra and Victoria for decades, and for its historic opposition to abortion, euthanasia and same-sex marriage.