Labor’s Western Australian Senate preselections are threatening to turn nuclear, with jockeying for positions commencing in earnest, even though nominations won’t be called until March 15.

A senior WA Labor source has suggested that dominant shop assistants tsar Joe Bullock would be elevated to the number 1 spot on the party’s Senate ticket, while others are accusing outsiders of leaking to the media as part of a deliberate destabilisation campaign.

In an incendiary Sunday interview on Perth radio station 6PR, veteran presenter Bob Maumill — not normally considered well briefed in party matters — popped up to give a curious interpretation of two live issues: the order of the Senate ticket at the September election and a replacement for retiring Chris Evans.

According to Maumill’s analysis, United Voice state secretary Dave Kelly was on the verge of cutting a deal with the right to elevate Bullock to the unloseable number one spot on the ticket. In return, Kelly would receive the SDA’s backing to parachute United Voice assistant national secretary Sue Lines into Evans’ spot. Under the deal, Pratt — who was number one in 2007 — would be forced into the tenuous number two spot. And Mark Bishop (a former SDA state secretary) would be consigned to number three, effectively ending his political career.

WA Labor’s expanded state executive will rule on the Senate pre-selection in mid-April following the upcoming state election. Its 170 members roughly comprise 100 Left members (in turn split 50/50 between the Pratt-supporting industrial left comprising the AMWU, the MUA, the CFMEU, the ETU on the one hand and the soft Left United Voice on the other). On the Right lies the SDA, the TWU and the AWU. In summary — unless it splits — the Left has the numbers.

The problem with the mooted deal is that the soft Left doesn’t need the support of the Right to parachute Lines (or anyone else) into Evans’ spot — it would receive no benefit from shafting Pratt. One sticking point could be a floppy “wannabe centre” comprising the MUA, CFMEU and ETU, who are increasingly looking to Dean Mighell in Victoria for guidance.

The senior ALP figure today suggested Maumill been influenced by “someone with a definite agenda” and had “used the prospect of a Bullock ascension as a trojan horse to preserve the status-quo”.

“They want a fight now … and then, after the state election, someone will call for calm and Mark will cut a deal to stay on the ticket,” they said. On the current numbers Bullock — if he wanted to roll his SDA predecessor — could probably snag the number two spot on his own.

However the number two WA Senate spot has become perilous — if Labor slips to 1.8 quotas or 27% of the primary vote, Bishop (or Pratt, or Bullock) would be in the crosshairs. In 2010, Glenn Sterle was elected with just on two quotas or 30%, but the party’s support in the state has since slipped.

WA state secretary Simon Mead, also mooted as a potential Senate candidate, declined to comment this morning, saying he was busy running a state election campaign.