Prime Minister Scott Morrison has written to NSW Liberal preselectors in "strong support" of former senator Jim Molan's tilt to return to Canberra.

The retired army major general's bid to fill a casual vacancy created by the resignation of Arthur Sinodinos has also won the backing of John Howard and Sydney-based broadcaster Alan Jones.

Prime Minister Scott Morrison has committed his 'strong support' to Jim Molan's return to the Senate. Credit:Alex Ellinghausen

In an email to delegates ahead of the vote on November 10, Mr Molan has circulated written references from the trio to let them know how he "might best help the Morrison government beat Labor [and] the Greens".

The party remains fractured over the potential for his return, with many still angry about his rogue campaign to convince people to disregard the Coalition's Senate ticket and vote for him "below the line" in the lead-up to the May 18 poll.