United Voice, which did a deal with Bullock's rightwing Shoppies, now says senator-elect is unfit to represent Labor

The leftwing union that did a deal to put controversial right-winger Joe Bullock at the top of Labor’s Western Australian Senate ticket is now calling for him to stand aside.

“In light of his recent comments we no longer believe he is fit to represent the ALP in the Australian Senate. If Joe Bullock really believes in the Labor party, if he believes in making Australia a better place, he should seriously consider resigning his position,” said Carolyn Smith, the secretary of United Voice WA.

Labor had a disastrous result in the WA rerun, suffering a 5% swing against it. On the final day of the campaign, Bullock was forced to apologise for a speech to a Christian group the previous year in which he attacked the party’s No 2 candidate, Louise Pratt, and described ALP members as “mad”.

Smith said the speech was the reason her union was calling on Bullock to stand aside – a call it has no power to enforce now that he has been elected.

“I believe the comments made by Mr Bullock were completely inexcusable. His description of party members was a betrayal of the many dedicated people who join our party because they believe in Labor as a party to stand up for ordinary people, for a decent life and a fair go. These are people who give generously of their time to campaign for a better Australia.

“His personal comments about Louise Pratt were appalling. We expect people in public life, particularly politicians, to hold a higher standard,” she said.

Smith said she had not spoken to Bullock personally before publicly calling for his resignation.

“I obviously have no control over what he does,” Smith told Guardian Australia.

“But given we endorsed him we had to make it absolutely clear that his comments about party members and about Louise Pratt were beyond the pale ... we knew about his socially conservative views but those comments were shocking."

Smith said she did not agree with Bullock's views on matters such as gay marriage, but "we had respect for his role as secretary of the shop assistants union".

Bullock was endorsed as the lead candidate on the WA Senate ticket under a deal between the rightwing faction, in which Bullock’s union, the Shop, Distributive and Allied Employees Association ( Shoppies), wields power, and the left faction, where Smith’s United Voice dominates.

The Shoppies had already agreed to their side of the bargain – that the assistant national secretary of United Voice, Sue Lines, be appointed to the casual Senate vacancy caused by the retirement of former minister Chris Evans. Lines does not have to face the voters until 2017.

The loser under the deal was the sitting leftwing senator Pratt. She appears likely to lose her seat in the rerun Senate poll, where she is battling for the last of the six seats with the third Liberal candidate, Linda Reynolds.

The state secretary of the Australian Manufacturing Workers Union, Steve McCartney, said he agreed with United Voice, but calling for Bullock’s resignation now wouldn’t change anything.

“I am not interested in posturing or Band-Aid solutions. I am not interested in waging campaigns through the media. I am interested in our movement, our ability to connect with working people and the future of progressive politics in Australia,” he said.