Boris Johnson has travelled to the United States to try and persuade Donald Trump not to pull out of the Iran nuclear deal.
The US president has fiercely criticised the agreement, which eased sanctions on Tehran in exchange for commitments to abandon its nuclear weapons programme.
Mr Trump will decide on May 12 whether to reimpose sanctions and effectively torpedo the international alliance behind the deal.
The Foreign Secretary is expected to appear on the Fox & Friends morning news show, which Mr Trump is know to avidly watch - frequently tweeting about items which appear on it.
The Foreign Office confirmed Mr Trump would appear on the show during his visit to the United States.
Mr Johnson will also hold talks with senior administration officials including vice president Mike Pence and national security adviser John Bolton.
Writing in the New York Times, Mr Johnson said: "Of all the options we have for ensuring that Iran never gets a nuclear weapon, this pact offers the fewest disadvantages.
"It has weaknesses, certainly, but I am convinced they can be remedied. Indeed at this moment Britain is working alongside the Trump administration and our French and German allies to ensure that they are."
British, French and German diplomats have been working for weeks behind the scenes with US counterparts in an effort to preserve the deal.
Mr Johnson said the deal had put restrictions on Iran's nuclear programme and "now that these handcuffs are in place, I see no possible advantage in casting them aside".
The UK's ambassador to the United States Sir Kim Darroch said the Iran agreement was "a good deal" but efforts were ongoing to "find some language, produce some action that meets the president's concerns".
He told CBS: "We have been talking at senior official level to the administration with our French and German colleagues for several weeks now.
"We think we're making progress.
"We haven't got there yet. We have a few days left to see if we can find a way through."
Sir Kim said that "Plan A is that the US stays in the deal" but "we are looking at all eventualities".