Alan Jones has labelled Matthias Cormann the 'n***** in the woodpile' and vowed 'not to yield' to those who find the 19th century phrase offensive.

The radio host used the term to describe the WA Senator as he discussed the Liberal leadership crisis, while calling on Malcolm Turnbull to resign and advocating Tony Abbott as the next prime minister.

'The n***** in the woodpile here, if I can use that expression, and I'm not going to yield to certain people who tell us that words in the language are forbidden, the person who's playing hard to get is Matthias Cormann,' Jones said.

The term has similarities to the colloquial phrase 'skeleton in the closet' and was used in the late 19th and early 20th centuries to describe a person who is the cause of a problem.

Alan Jones has labelled the WA Senator 'n***** in the woodpile' and vowed 'not to yield' to those who find the 19th century phrase offensive

Jones later apologised.

'We all make mistakes. This morning on 2GB and 4BC I spoke about the covert actions of some political operatives in the current leadership challenges within the Liberal Party,' he wrote on Twitter.

'I used an old and offensive figure of speech that I regret saying. People should be honest and forthright in their actions and that is not happening in the Liberal Party right now. I will have more to say on this tomorrow.'

Although usage of the phrase has declined dramatically since the early 1900s, Jones has repeatedly used it on live radio.

In 2013, then Deputy Premier of Queensland Jeff Seeney was labelled a 'n***** in the woodpile' - and the previous year so too was Mr Turnbull.

He used the term in 2011 to describe former Australian cricket captain and national selector Greg Chappell.

In 2007, he said on air: 'The Commonwealth is a bit of a n***** in the woodpile here'.

'N*****' is considered one of the most derogatory terms in the English language and 'is strongly racially offensive', according to the Oxford Dictionary.

'Recently the term has been reclaimed by some black speakers and used with positive connotations in various senses,' the dictionary states.

'However, even among black speakers, use of the word is problematic because of its potential to give offence.'

The radio host (pictured in May) later apologised and wrote on Twitter: 'We all make mistakes'

Meanwhile, Peter Dutton is demanding a second leadership spill after telling the prime minister he has lost the support of his Liberal party room.

'Earlier this morning, I called the prime minister to advise him that it was my judgement that the majority of the party room no longer supported his leadership,' Mr Dutton said at Parliament House on Thursday morning.

'As such, I asked him to convene a meeting of the Liberal Party at which I would challenge for the leadership.'

The former Home Affairs minister lost a challenge 48 votes to 35 on Tuesday but now wants to have another go at toppling his leader.

Peter Dutton is demanding a second leadership spill after telling the prime minister he has lost the support of his Liberal party room

It is believed Mr Dutton is now confident he has the numbers to force an extraordinary partyroom meeting and ultimately claim the leadership.

He has also released the legal advice which he says makes clear he is eligible to sit in parliament after questions were raised over his family's business interests in two childcare centres.

Questions have been raised if he could be in breach of section 44 of the constitution, which bans from parliament anyone who has 'any direct or indirect pecuniary interest with the public service of the Commonwealth'.