“There’s also an authenticity thing here that is appealing – you have a direct pipeline to what the president is thinking. The president also believes in cellphone diplomacy. He picks up the phone and calls people.”

Mr Trump used Twitter to impressive effect during his unconventional White House run. And he has continued to it as a powerful weapon in office, haranguing Lockheed Martin for the price of its F-35 fighter jet programme, for example.

There has been one concession, however. He appears to have traded his off-the-shelf Samsung phone for a new iPhone loaded with just a single app for tweeting.

That gives him instant access to his 31 million followers and much of his base.

But when it came to condemning Friday’s horrific attack on a Portland train by a knife-wielding Islamophobe, he chose a different channel. That message was delivered on his official Potus account which has 18 million followers and a rather different audience.

At the same time, it has emerged that Mr Trump has been giving out his mobile phone number to world leaders and asking them to call him directly, according to officials.

The practice breaks all diplomatic protocol as well as causing a headache for security officials charged with keeping his communications secure.