Paul Keating has come to the rescue of Anthony Albanese, using his first election campaign appearance to launch a withering attack on the "pathetic" Greens trying to unseat the Labor frontbencher.

The acerbic former prime minister was in fine form on Saturday as he emerged to excoriate the Greens, accusing them of splitting Australia's progressive vote and standing in the way of real reform.

"They're a bunch of opportunistic Trots hiding behind a gum tree trying to pretend they're the Labor Party," he declared in his address to the party faithful at the Petersham Town Hall in Mr Albanese's inner-western Sydney seat of Grayndler.