Nominations for candidate preselection in 21 safe federal seats in Victoria and one new seat opened on Tuesday and are due to close on Friday morning, in what some party members claim is an unprecedented rushed process.

In a last-minute hearing, a Victorian Supreme Court judge on Thursday night banned any finalisation of the process before 4pm Friday, dashing plans for the national executive to have confirmed candidates in safe seats by early afternoon.

The Victorian branch of the Labor Party is under the control of the party's national executive, after allegations of branch stacking were raised against former minister Adem Somyurek. He denies the claims.

The takeover means voting rights for Victorian party members who would ordinarily have a say in the preselecting candidates are currently suspended, and decision-making power is instead in the hands of the national executive.

But a group of ALP affiliated unions and their members have taken issue with the speed of the process.

"Preselection usually takes a minimum of two weeks but a two to three day setup, I'm instructed, is unprecedented," their barrister Ron Merkel QC told the urgent court hearing on Thursday.

Mr Merkel has been ordered to formally file by Friday morning.

He said there was obviously an "ulterior purpose" for the hasty process, suggesting it was designed to achieve "as little competition for nominations as possible".

"Looked at objectively, it looks like preselection stacking justified by branch stacking which has got nothing whatsoever to do with any conduct or misconduct alleged against the plaintiffs," Mr Merkel said.

As well as the federal takeover, Labor stalwarts Steve Bracks and Jenny Macklin were appointed as administrators of the Victorian branch and a review of membership was ordered to ensure the rank and file are all valid and paid up.

Mr Merkel said that process had ended in February, leaving no valid justification for "singling out" the 22 electorates three months later.

But Peter Willis SC, who is representing members of the national executive including federal Labor leader Anthony Albanese, says the process is entirely conventional and unremarkable.

One of the 22 seats is a new electorate, while the rest are considered "safe" seats where it's expected the sitting members will renominate and face little or no challenge, the court heard.

Mr Willis said preselection was in train in other states, including in Queensland and the Northern Territory.

He has also challenged the urgency of an injunction preventing the national executive going ahead with preselection because the result is not set in stone.

"If Mr Merkel has a winning argument then that argument will be upheld, and if it's upheld the process will have to be redone," he said.

"It's not really as if the situation would be irreparably or irretrievably changed."

He said while there is no date yet for the next federal election, it's possible a snap election could be called by the Liberal government as early as September.

Justice Tim Ginnane will hear more arguments on Friday.

Australian Associated Press