In a New Year's Day message 19 days before handing the reins to his successor Donald Trump, US President Barack Obama says the presidency has been a "privilege".

"It's been the privilege of my life to serve as your President. I look forward to standing with you as a citizen. Happy New Year everybody," he wrote on Twitter.

Obama used the social media network for a multimedia recap of the achievements of his nearly eight years as president, from health insurance reform and same- sex marriage equality to the fight against climate change and growth in the renewable energy sector.

"We traded foreign oil for clean energy, we doubled fuel efficiency standards, & we acted on a global scale to save the one planet we've got," he wrote.


Obama will hand over the presidency to Trump, who defeated Democrat Hillary Clinton in a bitterly contested election, on January 20 in an inauguration ceremony in Washington DC.

In an unusual move, the soon-to-be former president and first lady will remain in Washington until their younger daughter Sasha has finished school, moving from the White House to a rented home in the city's Kalorama district.