Bill Shorten.

Labor leader Bill Shorten. Photo: Andrew Meares

Opposition Leader Bill Shorten is warning that painful party reforms are just the start of a campaign to modernise Labor after its support reached a nadir in the West Australian Senate election.

Insisting that the party must change if it is to be taken seriously, Mr Shorten will push for an end to the rule requiring party members in some branches to join a union and says membership should be easier and cheaper.

In an address that was to be given in Melbourne on Monday, he planned to press for an ''honest conversation'' about the party's predicament and to call for the new system that gave party members a 50 per cent say in electing the federal leader to apply in every state.

Mr Shorten withdrew from the engagement after the death of a family member on Sunday. A spokesman confirmed the Opposition Leader was committed to the contents of the address.

He finished writing the speech after Labor suffered the same negative swing of about 5 per cent as the Coalition in the WA election - and attracted the primary vote of just one in five voters.

''Today is a day for facing up to some hard truths. Some of this won't be easy to hear - not all of it is easy for me to say,'' he wrote.

He conceded that the proposed reforms would not be painless but described them as far less painful than the alternative - ''a weaker, less-relevant Labor Party''.

Manufacturing Workers Union NSW secretary Tim Ayres, a member of the ALP national executive, said he was all for a "bigger Labor Party and a bigger Labor movement".

"That means we shouldn't put up barriers to people who share our values," he said.

"If we implement this change, we should make sure that Labor Party membership is a gateway for many people who aren't union members today, but who share our values to enter their unions and activism in their workplace."

However, Rail, Tram and Bus Union national secretary Bob Nanva said severing the link between the ALP and union membership should not be done in isolation. "It should only be considered as part of a package of reforms to make the union-party relationship more meaningful and productive," he said.

The controversy that enveloped Labor's lead candidate for the election, Joe Bullock, highlighted three of the party's biggest problems: its failure to attract and select quality candidates, the power of the factions and the perception that its links with the union movement are too close.

Revelations that Mr Bullock, a right-wing power broker and union leader, had described party members as ''mad'' and disparaged Labor's No. 2 candidate in Louise Pratt, derailed Labor's campaign in its final days.

But the party's problems are far more deep-seated than Mr Bullock's candidature, with insiders conceding that it will not be able to capitalise on the government's lack of popularity until it embraces fundamental change.

They say the biggest priority should be to change the way candidates are selected, especially for the Senate.

''Tony Abbott did not put Labor in opposition, the Australian people put us here, and unless we change, it is where we will stay,'' Mr Shorten planned to say.

He conceded that, for too long, Labor had seen its problems as about image, message and its ability to sell its policies.

''It's more serious than this. We need to change ourselves. We need to change our party,'' he wrote.

with Anna Patty