Tory leadership contender Jeremy Hunt is to outline his plans for a no-deal Brexit, including a £6bn pledge to the fishing and farming industries.
Setting out what he would do as PM, Mr Hunt will say farmers and fishermen “face uncertainty” if there is no deal, but that he will “help smooth it over”.
Some farming leaders have warned against leaving the EU without a deal.
Mr Johnson also promised to support the rural community after Brexit during a meeting with farmers last week.
Mr Johnson and Foreign Secretary Mr Hunt are competing against each other to become the next Conservative leader.
The Conservative Party’s 160,000 members will begin voting next week and Theresa May’s successor is expected to be announced on 23 July.
In a speech in London