By ITV News Content Producer David Williams
SNP leader Nicola Sturgeon will also warn that Scotland's NHS is "on the line" if Mr Johnson agrees to Mr Trump's apparent trade demands.
And at what point will the US president speak out?
Here’s what's in store today:
Prime Minister Boris Johnson is expected on the campaign trail before attending Nato events
Labour leader Jeremy Corbyn will attack bad bosses and insecure work, appear on This Morning and attend the reception at Buckingham Palace in the evening
Lib Dem leader Jo Swinson will visit a farm outside Chelmsford to discuss the impact of Brexit and a Trump trade deal on UK farmers
Brexit Party leader Nigel Farage will head to the East Midlands
SNP leader Nicola Sturgeon issues a Johnson-Trump trade warning in Perth on the future of Scotland's NHS
Here's more on Tuesday's election headlines:
The view from the campaigns
Paul Brand outlines the threat to the Conservative campaign from Donald Trump's presence in London.
Romilly Weeks says Jeremy Corbyn has a busy day ahead while taking advantage of Trump's arrival.
Rachel Younger says a compliment from Nigel Farage hasn't helped Jo Swinson's cause.
Emma Murphy says Farage is driving a message on national security as the party looks to build its support in the Midlands.
Calling Peston: The ITV News Election Podcast
Has the London Bridge attack been politicised?
A clearly quite moved Robert gives his analysis on the main parties' divided reaction to Friday's tragic killings in central London and thoughts on why it didn't lead to a suspension of campaigning (as in 2017).
There's more snap analysis from our experts around the country as Daniel indulges in his twin loves of motorways and politics.
Plus on a lighter note, the Calling Peston team welcome in December with the selection of their favourite Christmas songs and reminisce about the incredulous campaign moment from 2015 when David Cameron's true colours as a football "fan" were revealed.
ITV News Political Correspondent Daniel Hewitt and Political Reporter Shehab Khan are digesting the campaign every weekday - and dialing in Robert to get his take on it all.
The Calling Peston podcast is taking you behind the scenes of life reporting on the election campaign trail, hearing from our reporters on the road across the country.
Explained: How the General Election exit poll works
If you can't get enough of the Calling Peston co-hosts, here they are again in an enlightening chat with ITV's election expert Professor Colin Rallings.
He's part of the team that produces the exit poll you'll see at 10pm on election night on December 12.
The poll correctly predicted that the Conservatives wouldn't get a majority in the 2017 election. So how are those predictions reached?
Watch Colin take Daniel and Shehab through the process above.
Why the Tories face a serious BAME challenge in target seat three
The well-liked Labour MP Ian Austin stepped down at the beginning of the campaign telling people he was going to vote Conservative.
The area is 71% Leave and so all in, a perfect petri-dish of conditions in which to grow a Tory win.
That could well come to pass but I was a bit surprised by the force of the anti-Tory feeling from ethnic minority voters round here.
And while in the Midlands... here's a personal focus on a former powerhouse seat
I lived in both Kings Norton and Northfield itself between 1982 and 1984 back in my days as a student of English at Birmingham University.
The area's days as a powerhouse of traditional Midlands manufacturing were drawing to a close.
Mrs. Thatcher was in power at 10 Downing Street and the seat was held by a Conservative MP, Roger King.
It's been Labour since 1992. Parts of the area are still recognisable to me, but so much has evolved.
Today's question: Why have the Tories finally rushed to spend on Facebook ads?
Something seemed wrong.
How could this be from the Party that reportedly spent £1m in one day during the 2017 election?
The answer appears to be that they were waiting.
We don’t yet have the precise spending for the last 24 hours but we can see that they have significantly upped the amount of adverts they are producing.
Plus, as ever, here are your...
Here's the best of Monday's campaign stories:
What's happening away from the election?
Here's what else is making the news today: