The EU has repeatedly said it will not reopen discussion of the Brexit transition deal it reached with May a year ago, which British lawmakers have rejected three times, or to negotiate a future trade deal with Britain without the divorce payment.
Britain's Environment Secretary Michael Gove leaves the BBC, after appearing on the Andrew Marr Show, in London, Britain.
As his opponents fall away, Johnson's pledge to leave the bloc with or without an agreement on October 31 will be watched closely by markets that have in the past been spooked by the possibility of a no-deal divorce.
In his first major interview of the campaign, the bookmakers' favourite said only he could defeat the twin threat posed by the leaders of the Brexit Party and Labour - comparing them to the sea monsters from Greek mythology which troubled Odysseus.
During a brief initial stop in Ireland before the commemorations in France, Trump told Irish Prime Minister Leo Varadkar that the contentious Brexit issue of the Irish border would "work out very well".
Foreign Secretary Jeremy Hunt, another contender, also warned against the dangers of a general election, but said the only way to avoid one is to exit the European Union with a deal.
Johnson said withholding the £39 billion-pound financial settlement will be a "great solvent and a great lubricant" in forcing the European Union to offer a good deal to the UK. The current deadline is October 31.
In an interview in the Sunday Times newspaper Johnson said the funds would be retained until Britain got more clarity, describing money as "a great lubricant" when negotiating a deal.
Speaking to the Mail on Sunday, Javid said: "I think it's morally justified to pay for that because we both signed the Good Friday Agreement, we are both absolutely committed to peace on the island of Ireland and - given that we voted to leave and that's what's changing the status quo on the island and Ireland - I think it's morally right that we say, "look, we'll pay because we've caused this".
"The person had a mild Irish accent and said, 'This is the No. 10 switchboard, we have got the president of the United States for you; I am just going to patch you through to the White House situation room, '" Johnson, the former U.K. foreign secretary, told the Times.
Interior minister Sajid Javid, another of the eleven candidates to succeed May, said he might be prepared to oversee a no-deal Brexit, rather than miss the deadline but only as a last resort.
Javid and Johnson are among eleven candidates vying to replace Theresa May, who will remain prime minister until a successor is chosen.