Ambition and opportunity: Nats boss on PM

Nationals leader Michael McCormack says ambition, opportunity and poor polling are behind the ousting of Malcolm Turnbull as prime minister.

Nationals leader Michael McCormack says new PM Scott Morrison is doing well in the job. (AAP)

Why is Scott Morrison prime minister?

Nationals leader and deputy prime minister Michael McCormack has given the clearest indication yet as to why Malcolm Turnbull was rolled.

"There will be books written about it but the fact is, I guess, ambition, Newspolls, the economy was going well, the economy is going well," Mr McCormack told Sky News on Thursday.

"But when you combine those sorts of things, ambition and Newspolls and the like, and opportunity, you know people take those opportunities and we've got a new prime minister.

"But he has hit the ground running, he is doing very well, and I'm glad he has placed drought as his first priority."

Labor has been hectoring the prime minister all week to answer why Mr Turnbull was sacked.

Mr Morrison says it is time for the opposition to "get over it" and focus on the things that matter to Australians.