Victorian Liberals are openly defying the Prime Minister's call for them to quickly settle on candidates for the next election.

The delay in picking candidates is said by some to be due to a power struggle between the religious right and more moderate Liberals.

The Victorian Liberals are now controlled by a group of new conservatives — led by state vice-president Marcus Bastiaan, who has been accused by moderates of aggressively recruiting Mormons and Christian groups to branches across the state to get more social conservatives into Parliament.

After a state council meeting on the weekend, ABC News understands Mr Bastiaan used his influence to override the party's president Michael Kroger and suspend the Senate preselections, which were due to open on Monday.

Some Victorian Liberals believe the new conservative wing is positioning to replace first-term Senator Jane Hume on the party's ticket. Multiple sources said she is facing a considerable threat.

Multiple sources said Jane Hume is facing a considerable threat. ( ABC News: Nick Haggarty )

One possible challenger who has been named in despatches is Legal Aid lawyer and state vice-president Karina Okotel, who unsuccessfully ran for the Senate in 2016.

In an unusual move, Ms Okotel, an ally of Mr Baastian, is understood to have moved a motion late on Sunday withdrawing the party's resolution to open up preselections on the Monday, casting doubt over the political future of Senator Hume and Senator James Paterson.

Any moves against the senators would undermine Mr Turnbull, who has not only endorsed all sitting members — including Senator Paterson and Senator Hume — but also directed the states to sort out their candidates for the next election.

Senator Paterson has been endorsed by Mr Turnbull. ( ABC News: Andrew Kennedy )

Senator Hume is considered more moderate and has been targeted by conservatives — including commentator Andrew Bolt — who claim she has not done enough to protect "freedoms" and burnish her right-wing credentials.

Critics of the up-and-coming senator have been using a quip she made about young male colleagues who said "outrageous things to appease the far-right" as ammunition against her.

Campaign to 'infiltrate' Victorian Liberals

Sources have told ABC News, on top of the branch-stacking, there has been a concerted campaign by religious groups and social-conservatives to "infiltrate" the Victorian Liberals — particularly since the same-sex marriage survey.

At the state council meeting, former Family First candidate and Mormon doctor Ivan Stratov won a position on the administrative committee — the party's most powerful body.

The group of new conservatives are led by state vice-president Marcus Bastiaan. ( ABC News: Four Corners )

A senior Liberal acknowledged the change in power structure, saying the party had always been a broad church but "the weighting has slightly shifted".

Mr Kroger's presidency is now dependent on these "new adherents" — who comprise 721 votes out of state council, compared to 448 representing the old party, Liberal sources said.

The majority bloc of Victorian Liberals is now controlled by Mr Bastiaan and Liberal MP Michael Sukkar.

"Kroger saw [the Bastiaan-controlled bloc] as a benefit to him and now Kroger is only president because of them," a member said.

Michael Kroger's presidency is now dependent on the "new adherents". ( ABC News )

Old Liberals discomfited by new power structure's rise

The old wing of the Victorian Liberals has been discomfited by the rise of the new power structure.

A Liberal from the moderate faction said:

"These things have got to play themselves out, but political parties normally tear themselves apart from within — especially if they seek to take down a first-term woman senator [Jane Hume] who is doing very well."

"Jane is a classic Victorian Liberal — she is a backbencher with views of her own that don't accord with views heard on Sky News after dark."

Much of the new group's frustration has been directed at party's Victorian parliamentary team, with several sitting MPs nervous after the result of the weekend's state council, including the future direction of their party.

The disquiet comes at an awkward time for the party.

It has a state poll in November, and federally, the party faces a tough fight holding the marginal seats of Corangamite and Dunkley at the next election, while Labor will likely claim the new seat of Fraser.