Federal Opposition Leader Bill Shorten has declared a Labor Government would "stop the boats" and strongly indicated there will be no change in the party's border protection policy.

In a sign of how sensitive this issue is, the Victorian Labor state conference today shut down a potentially damaging debate over the party's policy on offshore processing.

The motion, drafted by Labor's left, urged the party to "close the offshore detention centres, transit centres and other camps on Manus and Nauru within the first 90 days" of a Shorten government.

But shortly before debate was due to begin, two powerful unions, the AWU and CFMEU, teamed up to defer that motion — and all others — prompting cries of "shame" from the audience.

Earlier, Mr Shorten moved to counter the Coalition's claims that Labor would "weaken" Australia's tough border protection policies, declaring "a Labor Government will stop the boats".

"The current Government would like to say that there'll be another policy; there won't be," he said.

"I'm very committed to making sure the boats don't start again.

"We also just happen to think that we shouldn't be leaving people in semi-indefinite detention for five years just to achieve this."

Labor members 'extremely disappointed'

Labor party members were shocked at the sudden end of the weekend conference.

"I'm extremely disappointed," Pauline Brown from Labor for Refugees said, holding back tears.

"I feel upset for the people who are still on Manus and Nauru."

Gavin Jennings, the Labor leader of Victoria's Upper House, said it appeared that unions were "playing games" because they were upset for not getting their way on internal procedural matters.

"There was a strange alliance of unions who decided they'd rather go home than talk about those important issues," Mr Jennings said.

"It was a combination of left-wing unions and right-wing unions that have not usually voted together."

CFMEU powerbroker John Setka, fresh from having blackmail charges dropped, told the ABC it was "democracy at work."

Labor's border protection policies largely mirror the Coalition's, but some of its MPs have recently started speaking out against the "indefinite" detention of refugees on Manus Island and Nauru.

Labor MP Ged Kearney has called for an end to "indefinite offshore detention". ( ABC News: Matt Roberts )

Newly elected Labor MP Ged Kearney used her first speech in Parliament to call for an end to "indefinite offshore detention" while frontbencher Linda Burney said there should be "time frames" and "limits" to how long refugees can be held.

The Coalition has seized on these statements as evidence of a "divided" Labor Party, with Cabinet Minister Greg Hunt telling Insiders "they are not committed to maintaining the current border protection regime".

While there is obvious tension within the party, Mr Shorten and senior colleagues, including Richard Marles, are determined to maintain a tough stance on border protection after the Rudd and Gillard policies which saw more than 50,000 asylum seekers reach Australia by boat.

Mr Marles has cautioned against putting time limits on offshore detention, but insisted Labor's approach was "very different" to the Coalition's, pointing to the party's pledge to increase Australia's refugee intake and work more closely with the UN's refugee agency.

None of the votes at today's state conference would have been binding — the party's policies are set at the national conference which has been deferred because it clashes with the date of the five looming by-elections.

Editor's note (29/05/2018): This story has been updated to correctly reflect the charges brought, and later dropped, against John Setka.