The dominant Victorian arm of the National Union of Workers has formally resolved to back progressive ALP delegates in their conference fight with Julia Gillard over gay marriage, drawing the Left to within striking distance of slapping down the prime minister's preference for a self-defeating conscience vote.

Crikey can reveal that at a high-level meeting of NUW delegates held last night at the union's Docklands offices, the seven-strong group formally resolved to vote to remove references to John Howard's Marriage Act from the party's platform and object to the PM's conscience cop-out which would effectively keep gay nuptials outlawed in league with Tony Abbott.