A former Republican group chairman has said he would not vote for Donald Trump again even if the president walked on water.

Speaking from a rally in Minneapolis last week, Mr Trump said his first steps towards ending the ongoing trade war and reaching an accord with China would bring in $50bn of farm purchases from the eastern superpower.

But soybean farmer Christopher Gibbs, a former chairperson of the Shelby County Republican Party in Ohio, said he would not believe the president until the beans were on the boat – adding that Mr Trump’s promises felt like “déjà vu”.

“The president promised massive purchases from Mexico”, Mr Gibb said.

"He’s promised massive purchases from the EU and now he’s promising massive purchases from China. He’s done this before.”

Shelby County backed Mr Trump by 18,590 to Hilary Clinton’s 4,243 in the 2016 election. And while Mr Gibb supported him then, he insisted he would not vote for the president again.

"I’m not going to vote for the president and it doesn’t matter what he comes up with now” Mr Gibb added.

“He could come up with this $50bn, he could walk across my pond and not get wet, and I’m still not going to vote for him because, you know, at the end of the day my name is Chris Gibbs, it’s not Judas, and I’m not going to sell my political moorings for 30 pieces of silver."

Announcing the deal at a rally in Minneapolis, Minnesota last week, Mr Trump told the crowd: “I love my farmers”.

He added: “In fact, the biggest problem it'll be $40bn to $50bn in farm purchases. I don't think our farmers can produce that much — I said, that's okay.

“You know my people said 'Sir, could we make it 20 instead?' No, make it 50! Our farmers will buy more land and they'll buy bigger tractors by now,”.

However the pledge by China to double its purchase of agricultural products is yet to be fully agreed – and is expected to make up part of a broader raft of concessions from Washington and Beijing to signal an end to the trade war both sides have engaged in.

Beginning in 2018, the tit-for-tat introduction of tariffs has directly hit constituencies the president courted during his campaign for the White House – including soybean farmers and steel workers.