Molan allies including party elder Walter Villatora, John Crawford and Sean Burke could face repercussions for their unauthorised campaign that asked voters to disobey Liberal how-to-vote cards and instead vote below-the-line in support of Senator Molan.

In a separate matter under review, former Liberal MPs Joanna Gash and Ann Sudmalis are under the microscope for campaigning for the Nationals' candidate Katrina Hodgkinson - instead of the Liberal candidate Warren Mundine - in the seat of Gilmore.

Senator Molan is accused of confusing voters, undermining or breaching the Coalition agreement with the National Party and jeopardising the Liberal campaign by recruiting volunteers who should have been helping other candidates.

In particular, he enlisted a large number of volunteers to hand out how-to-votes in former prime minister Tony Abbott's former seat of Warringah on Sydney's northern beaches.

While Senator Molan's activities were not discussed at the party's most recent state executive meeting, several members say they have been privately assured by state director Chris Stone that an inquiry is underway.

It is considered unlikely that Senator Molan will himself face disciplinary action. But the concerns held by figures at the highest levels of the NSW Liberal Party make it less likely Senator Molan will win the support of preselectors to fill the Senate vacancy when Arthur Sinodinos becomes United States ambassador.

Asked whether an investigation was afoot, NSW Liberal Party president Philip Ruddock said that when complaints were made, party members could expect them to be investigated.

One irate member of the state executive said: "We're keen to do something to discipline the people that ran the [Molan] campaign. If they don't do something, we'll start pushing it."

Another said: "It is likely that the ringleaders will face some kind of disciplinary action. It'shighly unlikely that Jim Molan will get the Senate spot. People are quite angry."

In an escalation of the tensions besieging the division, Senator Molan is also preparing to launch legal action against a fellow Liberal MP, Trent Zimmerman, for describing his rogue campaign as "dishonourable".

Mr Zimmerman, a former NSW Liberal Party president, has called for new rules to punish candidates who engage in unauthorised below-the-line campaigns such as Senator Molan's.

International Development Minister Alex Hawke, who is Prime Minister Scott Morrison's representative on the NSW Liberal Party's state executive, has denied claims that factional forces were attempting to expel Senator Molan from the party.

An army major-general who served a year as chief of operations for the coalition forces in Iraq, Senator Molan was a key architect of Operation Sovereign Borders and a special envoy for then prime minister Tony Abbott.

He was elected to fill a Senate vacancy in 2017 when Fiona Nash was disqualified over dual citizenship. However, preselectors relegated him to the unwinnable fourth position on the joint Coalition Senate ticket in NSW. Senator Molan said he had no issue with the Liberal Party conducting a post-election review.

The Liberal Party's review will also examine the actions of Ms Sudmalis and Ms Gash, who endorsed and campaigned for the Nationals candidate in Gilmore rather than the Liberal.

Prime Minister Scott Morrison controversially intervened and turfed out the preselected candidate to install Mr Mundine. Gilmore was the only seat in the country Labor won off the government that was not already a notionally Labor seat following the redistribution.