US President Barack Obama's tweet following his farewell address to the nation has become the most popular post on the presidential account - and exceeds his successor's most retweeted message by half a million shares.

Shortly after concluding his speech in Chicago on Tuesday night, Mr Obama tweeted from the @POTUS account: "Thank you for everything. My last ask is the same as my first. I'm asking you to believe - not in my ability to create change, but in yours."

As of early on Thursday, the message had been retweeted more than 715,000 times.