A CO Down dairy farmer, who voted to leave the EU, says he now regrets his decision and claims Boris Johnson's pledges about giving more money to the NHS were "lies".
Waringstown man Charlie Weir, who appeared in a DUP election broadcast, said a no-deal would lead to a collapse in milk prices and that he now supports the backstop.
In the 2017 election broadcast he said he believed the DUP "cared about agriculture and wanted to make agriculture more sustainable".
In the same broadcast, DUP leader Arlene Foster said: "Farmers like Charlie know the opportunities that leaving the European Union will present, as well as acknowledging the challenges."
She said only her party could "secure the best deal for Northern Ireland".
However, Mr Weir has changed his mind and said he would no longer vote for Brexit.
He said farmers were currently selling their milk at below the cost of production and that processors had warned of a another significant drop in prices in the event of a no-deal Brexit.
Mr Weir said such a collapse in prices would "finish the dairy industry in Northern Ireland".
"We would be going onto World Trade tariffs and that would reduce our milk price by 30 per cent," he said.
He said he voted to leave the EU in the June 2016 referendum because he believed Boris Johnson's claim that money going to Brussels would be diverted to the NHS and "make the country a better place".
"But that was all lies so if I'd have known this at the start I'd have never voted to leave," he told the BBC.
"If we leave now the Cap (Common Agricultural Policy) money wouldn't be paid into Northern Ireland agriculture and farmers in Northern Ireland receive £300m a year from that."
Mr Weir said he was aware of the challenges that Mr Foster referred to but "we never thought we were leaving without a deal".
He said he would vote for the DUP again but that the backstop would not lead to a united Ireland and that the insurance policy against a hard border had been "built up into something that it's not really".
