Victorian Premier Daniel Andrews has stepped up Labor's attack against Malcolm Turnbull over marriage equality, lashing out at the Prime Minister for allowing a "cowardly" plebiscite because he is too beholden to the right wing of his party.

With one week before the federal election, Mr Andrews made a last-minute appearance at a marriage equality rally in Melbourne on Saturday, telling protesters that real change could only be delivered by a government that is genuinely ready to reform.

The rally at the State Library. Credit:Luis Ascui

Contrasting the actions of his own administration - which has delivered on gay adoption in Victoria; supported the Safe Schools program; and initiated a state apology for past convictions of homosexuality – Mr Andrews attacked Mr Turnbull for endorsing a public vote "instead of politicians doing what they're paid to do, which is to make laws and change laws."