The president has repeatedly praised the Prime Minister, claiming people call Mr Johnson “Britain’s Trump” because of their similar styles.
On October 31 – the day the UK was supposed to leave the European Union – Mr Trump said he wished Mr Johnson and Nigel Farage would team up to form an “unstoppable force”.
Describing them as “two brilliant people”, the US president called for the Prime Minister and the leader of the Brexit Party to “get together”, in what was viewed as him encouraging the two men to form an electoral pact.
Mr Trump hailed Mr Johnson as “the exact right guy for the times”, but also criticised his Brexit deal, claiming it hinders trade with the US.
It would be fair to say Mr Trump likes Mr Johnson, yes?
It would certainly seem so. Speaking at the start of the Nato summit – with just over a week to go before voters go to the polls – Mr Trump said he thinks Mr Johnson is “very capable”, adding: “I think he’ll do a good job.”
At the weekend, when asked if the president will be briefed not to wade into the General Election on his trip, a senior US administration official said the president is “very conscious” of the fact “we do not interfere”, but added: “He also, as I suspect you know, likes Boris Johnson – Prime Minister Johnson, personally.”
Mr Trump said during the summer that Mr Johnson is “exactly what the UK has been looking for”.
While praising Mr Johnson, Mr Trump was less positive about the Labour leader back in October, warning: “Corbyn would be so bad for your country, he’d be so bad, he’d take you on such a bad way. He’d take you into such bad places.”
Mr Corbyn hit back at the criticism, saying Mr Trump was interfering in a bid to “get his friend Boris Johnson elected”.
What does Mr Johnson say about all of this?
Ahead of Mr Trump arriving in the UK this week, the Prime Minister said: “When you have close friends and allies like the US and the UK, the best thing is for neither side to get involved in each other’s election campaign.”
As Foreign Secretary in 2016, Mr Johnson told Europeans to cease their “collective whinge-o-rama” over Mr Trump’s triumph, and has praised the president for having “many, many good qualities”, celebrating him for having “got the US economy motoring along”.
But Mr Johnson has not always been so positive about the US President. As London mayor in 2015, he described Mr Trump as “clearly out of his mind” and “unfit” for the White House when the then-presidential candidate called for a ban on Muslims entering the US.
Where does Jeremy Corbyn stand?
The Labour Party has repeatedly claimed that the health service is “on the table” in a post-Brexit trade deal with the US.
What do the Liberal Democrats think?
Following the president’s insistence about the NHS, Liberal Democrat foreign affairs spokesman Chuka Umunna said Mr Trump has “repeatedly made clear” that everything, including the NHS, is on the table in future negotiations.
“Like Boris Johnson, Donald Trump is hardly known for his honesty. Voters will rightly take these comments with a lorry load of salt,” Mr Umunna said.
Lib Dem leader Jo Swinson has previously said Mr Johnson is “modelling himself” on the US president.
Ms Swinson said that that while she would not refuse to engage with Mr Trump there is a “big difference between having a relationship and engaging, and rolling out the red carpet”, which is what she said the Tory Government has done.