Boris Johnson will make his first visit to Wales as prime minister on Tuesday, as he tries to rally support for his plan for farming after Brexit.
He is expected to promise agriculture will continue to thrive after Brexit.
It follows the Farmers’ Union of Wales president warning of “civil unrest” in Welsh rural areas if the UK leaves the European Union without a deal.
He will also meet Wales’ First Minister Mark Drakeford, who said the PM has “no public mandate for a no-deal Brexit”.
Mr Johnson’s visit is the latest in his tour of the United Kingdom since becoming prime minister, after a trip to Scotland at the start of the week.
On Monday, the prime minister said there was “every chance” a Brexit deal with the EU could be struck, but the existing agreement with the EU has “got to go”.
But senior minister Michael Gove has said the UK government was working on the assumption the UK would leave the EU without an agreement.
Mr Johnson’s visit to Wales comes as the Conservatives fight to hold Brecon and Radnorshire seat in a by-election.
Ahead of the visit, the prime minister said: “I will always back Britain’s great farmers and as we leave the EU we need to make sure that Brexit works for them.
“That means scrapping the Common Agricultural Policy and signing new trade deals – our amazing food and farming sector will be ready and waiting to continue selling ever more not just here but around the world.
“Once we leave the EU on 31 October, we will have a historic opportunity to introduce new schemes to support farming – and we will make sure that farmers get a better deal.”
Agriculture and what will replace CAP farming subsidies are devolved to the Welsh Government
Ministers in Wales have proposed two grant schemes to replace EU funding, with farmers offered cash to carry out work that protects and enhances the environment.
Welsh farmers receive subsidies worth about £300m a year from the EU – it is not known how much cash will be available to support agriculture after Brexit.
Ahead of his meeting with Mr Johnson, Mr Drakeford said: “He has no public mandate for a no-deal Brexit, which would be catastrophic for Wales.
“If the UK does leave the EU, the UK government must work in close partnership with the Welsh Government to mitigate negative effects on Wales and its economy.”
A report commissioned by the Agriculture and Horticulture Development Board, Quality Meat Scotland and Meat Promotion Wales suggested beef and lamb exports to Europe could fall by about 92% in a no-deal scenario.
On Monday, Mr Johnson visited Faslane naval base in Scotland and announced £300m for three economic growth deals in Scotland, two in Northern Ireland and one in Wales – the Mid Wales Growth Deal.
It is not clear how much the mid Wales deal will receive – the UK government said it depended on the proposals put forward.
Meanwhile, two committees have been set up as the UK government intensifies preparations for a possible no-deal exit, including a “daily operations committee” of senior ministers.
On Monday, the pound sunk to a 28-month low against the dollar, apparently due to concerns about Brexit.