London (CNN) Donald Trump is a very unpopular man in the UK . Which is unfortunate, given he's here for the next couple of days for a meeting of NATO leaders.

First, there's the build-up, in which political groups across the spectrum announce their plans to protest against Trump as soon as he sets foot on British soil.

Then there's the President's obligatory dig at Sadiq Khan, the popular Mayor of London, over the city's knife crime epidemic. He might skip that tradition this time, given the deadly terror attack that took place in London last week. But his dislike of Khan is profound, and it could be too tempting.

There's usually a "surprise" newspaper interview, in which he sticks his nose into British politics and offends a major political figure. That's often followed by a press conference where he tries to clean up the mess, but usually just ends up tying himself in a knot of contradictions.

Finally, when all official business is done, he throws opens his doors to his favored British friends (think Nigel Farage and Piers Morgan) desperate to show off their closeness to the most powerful man on earth.

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The visits are usually more of a spectacle than anything else. This time, however, Trump lands just a few days before the UK holds what could be the most important general election in the nation's postwar history. And any unexpected grenades Trump chooses to hurl could have consequences beyond a two-day political storm and affect the outcome of an actual election.

In a Tuesday morning press conference, Trump told reporters that he would "stay out" of the UK election, before endorsing Boris Johnson and wading into a huge spat over Britain's National Health Service.

Trump has already been used as a political weapon to attack Boris Johnson during this campaign. The main opposition Labour Party, led by Jeremy Corbyn, has been telling anyone who will listen that one of the biggest threats a Johnson-led Brexit poses to the UK is him rushing to do a trade deal with Trump, and in doing so, sell out the country's revered National Health Service. And while the veracity of this claim is open to debate, the fact that it hurts Johnson is not.

It's not just about the NHS. Any association with Trump is likely to turn off the swing voters that Johnson needs to win over if he's to win a majority on December 12. And Johnson knows this. Since the campaign kicked off, he's been doing everything he can to avoid talking about the President. He dodges questions. The Conservative Party's Twitter account has mentioned Trump precisely zero times. He's the man no one wants to dance with.

Trump's toxicity is the reason Johnson's inner circle advised that he avoid the President during his state visit last summer, and why the Prime Minister is being so evasive about any potential meetings this week. It's also the reason Johnson will be privately hoping Trump keeps quiet, and definitely doesn't call him his "friend" again.

Corbyn, meanwhile, will be only too happy for Trump to pipe up. The President's last intervention consisted of not just an endorsement of Johnson, but a personal attack on Corbyn himself, saying he would take the UK to "such bad places". It was a moment that Corbyn, who paints himself as a sort of anti-Trump, can point to every time he wants to put clear water between himself and Johnson.

During a televised debate on Sunday night, Labour's Richard Burgon got stuck in, saying Trump wants to "conspire" with Johnson and "get his fat cat friends access to the NHS." The other opposition parties didn't miss out on this freebie, either. Jo Swinson, leader of the pro-remain Liberal Democrats, said "the current occupant of the White House is not someone who shares our values," while Adam Price, the leader of Plaid Cymru, the Welsh nationalist party, said that it "can never be acceptable for a man to talk about grabbing a woman's p****."

The only person on the stage willing to defend Trump was Farage, leader of the Brexit Party. The two have a personal friendship and Trump has controversially suggested that he should form a pact with Johnson for a big Brexit majority -- a move that would almost certainly cost the Prime Minister some of those all-important swing voters.

It's going to be a tense few days for the UK's political class. With barely any time left till the election and Johnson's poll lead holding firm, he will be counting the minutes till Trump's back in the air and heading home. Corbyn and the rest will be praying that the temptation to say something controversial is too great for the President -- don't be surprised if they bait him. And Nigel Farage will probably be sitting around waiting for his brief audience with Trump, reminding everyone -- including Johnson -- that he has the President's ear.

Trump's last two visits to the UK have been a total circus, but swiftly forgotten. This time, he walks into a high-stakes election that will ultimately determine what happens next in the Brexit saga. The fact that a US President -- who is himself in favor of a very hard Brexit -- has any influence in its outcome is problematic. The question is: can Trump's ego resist the urge to make itself the most important politician in another country for 48 whole hours?