President Barack Obama has taken a swipe at Donald Trump just weeks before his successor is due to take office claiming he would have won a third term in office in an election against the billionaire.

In a CNN interview with his former adviser David Axelrod on Tuesday, Mr Obama said he believed his vision for the country would have defeated Mr Trump.

“I am confident in this vision because I’m confident that if I had run again and articulated it, I think I could’ve mobilised a majority of the American people to rally behind it,” said the outgoing President, who was prohibited by US law from running for a third term.

Mr Obama’s comment drew a swift rebuke from Mr Trump.

President Obama said that he thinks he would have won against me. He should say that but I say NO WAY! – jobs leaving, ISIS, OCare, etc.

— Donald J. Trump (@realDonaldTrump) December 26, 2016

The world was gloomy before I won – there was no hope. Now the market is up nearly 10% and Christmas spending is over a trillion dollars!

— Donald J. Trump (@realDonaldTrump) December 26, 2016

Mr Obama also said Ms Clinton’s campaign had played it safe, and that while her economic message was “progressive”, it was “not widely understood”.

Don DeBats, head of American Studies at Flinders University, said Mr Obama had waded into the post-election debate because he was worried his legacy “won’t survive”.

“I think that’s what happens to most presidents. They want know how they will be viewed in the historical memory of the country,” Mr DeBats told The New Daily.

“I’m sure he’s sad Clinton is not there to continue [his legacy] and that Trump will eradicate a good deal of it.”

Staffing scandal

Experts say Mr Obama’s comments were directed at Mrs Clinton. Photo: AAP

Mr Obama’s comments come as Mr Trump was dealt a blow over Christmas, with campaign aide Jason Miller turning down an appointment as communications director amid rumours of an affair with another transition official.

Mr Miller said he declined the role to spend more time with his family, in a statement reported by CNN.

Despite being outspoken against each other in the run-up to the US election, Mr Trump and Mr Obama have both managed to remain ‘presidential’ and contain their their criticisms since the Republican’s victory.

Yet staff for both men have continued to clash, mostly over claims of Russian interference during the election and foreign policy.

Mr Trump will take office after his official inauguration on January 20, but he has already courted controversy as he transitions to the White House.

His desire to include his daughter Ivanka in his administration has raised eyebrows, as has the appointment of ExxonMobil chief executive Rex Tillerson to the position of secretary of state.

Mr Trump’s desire to see daughter Ivanka join him in the White House has raised eyebrows. Photo: Getty

Preparations for Mr Trump’s inauguration ceremony have also been bumpy, with suggestions Andrea Bocelli chose not to perform following a backlash and that Radio City Rockettes were also unhappy about being asked to perform.

More criticism to come

After the November election, Mr Obama revealed plans to withhold criticism of his successor, saying he wanted to be “respectful of the office and give the president-elect an opportunity to put forward his platform”.

University of Melbourne political expert Dr Raymond Orr said he would not be surprised if Mr Obama became a vocal critic of Mr Trump in future.

President Barack Obama says he could’ve beaten Donald Trump. Photo: Getty

Without a clear leader of the Democratic Party, the outgoing president might need to “take a stronger approach”, Dr Orr told The New Daily.

He said he would expect the pair to continue to clash during the transition period.

“I suspect everybody knows that Donald Trump has pretty thin skin,” Dr Orr said.

In the CNN interview, Mr Obama said he would focus on writing a new book after leaving the presidency.

“I have to be quiet for a while. And I don’t mean politically, I mean internally. I have to still myself.”