The political career of an outspoken Liberal Party backbencher appears secured, with New South Wales party officials voting to endorse all sitting federal MPs.

Key points: Conservative Liberal MP Craig Kelly was facing a preselection challenge he was unlikely to win

Conservative Liberal MP Craig Kelly was facing a preselection challenge he was unlikely to win Scott Morrison asked NSW party officials to step in and protect incumbent MPs facing a challenge

Scott Morrison asked NSW party officials to step in and protect incumbent MPs facing a challenge Malcolm Turnbull had urged party officials not to "capitulate" to Mr Kelly's threats to go to the crossbench if not preselected

The ABC understands Prime Minister Scott Morrison directed the NSW State Executive to intervene in the preselection process to avoid a potentially ugly internal brawl and ensure Mr Kelly remains a Liberal.

The outspoken backbencher had threatened to quit the party if he lost preselection but the party's intervention means he would not face a challenge.

It comes after an extraordinary intervention from the former prime minister Malcolm Turnbull, who publicly attacked the plan.

MPs first learned of the move on Sunday, and those from the moderate faction immediately tried to shut it down, believing it was a "smoke-screen" to protect Mr Kelly – an ally of former prime minister Tony Abbott.

While they worked behind the scenes, Mr Turnbull got wind of the plan, picked up his phone and wrote a series of tweets slamming the proposed move.

As one MP put it, the contribution was "distinctly unhelpful" and almost guaranteed Mr Morrison's plan to endorse all members would succeed.

Another MP accused Mr Turnbull of outright hypocrisy given he saved Mr Kelly, Angus Taylor and Concetta Fierravanti-Wells from preselection challenges in the lead-up to the 2016 election.

"He's saying 'don't do what I did three years ago'," one Liberal said.

"There's a lot of anger at Malcolm over the way he's handled this."