Scott Morrison labelled an ‘autocrat and bully who has no moral compass’ by Liberal senator Concetta Fierravanti-Wells

Liberal senator Concetta Fierravanti-Wells has launched an extraordinary attack on the prime minister, Scott Morrison, in parliament, labelling him an "autocrat [and] a bully who has no moral compass".

The senator - who has recently been relegated to an unwinnable spot on the Liberal party's NSW Senate ticket - used a late-night speech in the upper house on Tuesday to accuse the prime minister of destroying the Liberal party.

Fierravanti-Wells told the Senate that Morrison was "not fit to be prime minister" and claimed he had "destroyed the Liberal party" through recent interventions in NSW branch preselections.

She also accused the immigration minister, Alex Hawke - who is Morrison's lieutenant and a key factional player in NSW - of "corrupt antics" inside the Liberal party as she complained of losing her spot on the ticket ahead of the May election.

"In my public life, I have met ruthless people. Morrison tops the list followed closely by Hawke," she said. "Morrison is not interested in rules-based order. It is his way or the highway. An autocrat, a bully who has no moral compass."

She also took aim at Morrison's public profession of his evangelical religion, saying his actions "conflict with his portrayal as a man of faith".

"He has used his so-called faith as a marketing advantage."

Fierravanti-Wells earlier this week accused the party of having its own "mean girl" culture and spoke about "the stress associated with factional warfare".

On Tuesday night, just hours after the federal budget was handed down, the senator gave a speech in the upper house during which she stated: "There is a very appropriate saying here - the fish stinks from the head."

Fierravanti-Wells said Morrison and Hawke had ruined the Liberal party in NSW by trampling its constitution.

The senator was heavily critical of the recent preselection process which had been long-delayed until the national executive took over the division allowing Morrison and Hawke to install favoured candidates including sitting members.

She claimed the process had led to "captain's picks" which party members opposed.

"I have received hundreds if not thousands of emails outlining their disgust. They have lost faith in the party. They want to leave," Fierravanti-Wells said in the Senate.

"They don't like Morrison and they don't trust him. They continue to despair at our prospects at the next federal election. And they blame Morrison for this. Our members do not want to help in the upcoming election. Morrison is not fit to be prime minister. And Hawke certainly is not fit to be a minister."

Comment was sought from Morrison. A spokesperson for Hawke declined to comment.