MALCOLM Turnbull's Cabinet voted to support Kevin Rudd's bid to become the next secretary-general of the UN, until the Prime Minister apparently nixed debate in favour of a captain's call.

Unnamed sources have told Fairfax Media the question was taken to Cabinet, which was voting 11 to 10 in favour of supporting the former Labor Prime Minister's nomination, with Deputy PM Barnaby Joyce saying he would support whatever decision Mr Turnbull made.

In a Cabinet of 23, it was those two votes that would have swung the outcome.

Ultimately Mr Turnbull ended the discussion and told the room he would make a "captain's call".

He would later quash Mr Rudd's plans for the UN, telling him he lacked the appropriate skills for the job.

"Does the Government believe, do we believe, do I as Prime Minister believe that Mr Rudd is well suited for that role? My considered judgement is that he is not," Mr Turnbull told reporters.


Its understood ministers in Cabinet supported the case of Deputy Liberal Leader and Foreign Minister Julie Bishop, who put forward the "DFAT case" on behalf of Mr Rudd.

The decision to kybosh Mr Rudd's ambition also appeased the right wing faction of the Coalition.

Mr Joyce has previously said it was not a captain's pick, but a decision made by Cabinet.

However an unnamed Coalition minister told the AFR "the split was Rudd's way" before Mr Joyce and the Prime Minister swung the vote themselves.

Mr Rudd has since leaked letters he sent to Mr Turbull in which he claimed the Prime Minister supported his bid.

That has been denied by the PM.

Mr Rudd has since been captured on camera describing Mr Turnbull as acting like a "brick wall" in the face of his ambitions.

At the same event, he said even with hard work some best laid plans could "turn to s---".