"It's so much easier today to be a cynical poseur than a committed democrat, it's easier to retreat to observer status than convince your friends of the merits of incremental change," she said.

She cited the example of Medicare. Labor's push for a national health system began in the 1940s under Ben Chifley, but it was not established until 1983 under Bob Hawke.

"It required hard slog to ensure those institutions could survive the heat of adversarial politics. Then it took election campaign after election campaign, tough political negotiation, administrative effort, and the making and breaking of careers and governments to finally make Medicare stick," she said.

"The creation of Medicare took more than a hollow-principled stand, it took more than just wishful thinking, it took more than slogans, it took more than protests. It took real, tough politics. It took idealists who were prepared to fight to win government."

David Rowe

Ms Plibersek, whose seat of Sydney is a Greens target, said the DLP, formed when Labor split in the 1950s, kept the ALP out of power until 1972 because it divided the progressive vote.

"We risk a similar story in contemporary politics, between Labor and the Greens political party," she said.

"This is because the Greens see Labor, not the Coalition, as their true competitor and enemy. The Greens' political strategy risks entrenching conservative governments."


She blamed the Greens for Australia not having a carbon price today because they voted down the scheme negotiated between Kevin Rudd and Malcolm Turnbull in 2009 because it was not "perfect".

On Tuesday, shadow treasurer Chris Bowen re-emphasised Labor would rather stay in opposition than ever again govern in coalition with the Greens.

But Treasurer Scott Morrison released a new attack ad entitled "the Greening of Labor" .

"A Greens-Labor-Independent government is a very real prospect," he said.