Acting Prime Minister Warren Truss has avoided questions over his tenure as leader of the National Party, saying he is under no pressure to resign.

The Prime Minister's Office said late last year that a ministerial reshuffle prompted by the departures of Jamie Briggs and Mal Brough would be affected by the actions of the veteran MP.

But Mr Truss denies that statement put pressure on him to announce his retirement.

"Obviously it's my decision when I choose to make a decision whether I'm going to go on forever or whether one day I'll retire," he said.

"That's a decision for me to make, he [Prime Minister Malcolm Turnbull] has made that very publicly clear ... It's no secret that I had a very good working relationship with Tony Abbott and I'm looking forward that kind of relationship growing and strengthening also with Malcolm Turnbull."

Mr Truss also said that last year's failed attempt by Ian Macfarlane to defect from the Liberal to the National Party room had not damaged his relationship with Mr Turnbull.

He said that he expected the Prime Minister to address calls for an additional cabinet position for the Nationals when the reshuffle was announced.

"It's been recognised that as a result of the expansion of the inner cabinet that the Nationals are entitled to another position," he said.

"That essentially happened at the time of the change of leadership ... Malcolm Turnbull's made it clear that that issue will be addressed when there's a reshuffle in the future."

Barnaby Joyce a 'capable contender', Warren Truss says

Nationals Deputy Leader Barnaby Joyce has repeatedly announced his intention to lead the party when Mr Truss retires.

Barnaby Joyce (centre) has been touted as a likely replacement for Mr Truss (left). ( AAP: Alan Porritt )

Mr Truss said there was a "great depth of talent" in the party when asked on Mr Joyce's ambitions.

"Barnaby Joyce is the deputy leader and deputy leaders have a fairly strong record of moving on towards leader," he said.

"I'm sure Barnaby will be a very capable contender when and if a vacancy occurs."

Mr Joyce's push has been backed from a number of Liberal frontbenchers, with Christopher Pyne describing the MP as "focused".