On Thursday, Johnson raised the issue with the visiting US Vice President Mike Pence. “The National Health Service is not on the table as far as negotiations go,” Johnson said. “We’re not too keen on the chlorinated chicken, either.”

Referring to Labour leader Jeremy Corbyn, he added: “We have a gigantic chlorinated chicken of our own here on the opposition benches.” It’s the second time this week Johnson has used the insult.

According to the tender seen by BuzzFeed News, the US wants to fight back against what they call “misconceptions” about the American farming industry, which could put a US-UK free trade deal at risk.

“The misconceptions include animal welfare standards, GMOs and labeling, and the use of antibiotics in livestock production,” the tender says. “Media stories about ‘industrial scale’ U.S. agriculture, usually focused on so-called ‘chlorinated chickens’, are negative, misleading, and often inaccurate.”

The winning bid will be paid between £60-75,000 to organise a press trip for “influential” UK journalists and activists as they tour American farms.

“Participants will explore small, medium, and large farms representing various certification standards (organic, natural, conventional), research institutions supporting science-based agricultural practices, government agencies that focus on ensuring food is nutritious and safe, and other relevant institutions connected to U.S. farming,” the tender reads.

“The locations should be carefully chosen to be geographically and culturally diverse and reflect the breadth of choice the U.S. consumer has when making food decisions.”

The tender also cites US Department of Agriculture (USDA) polling done in the last year by Gallup, which revealed twice as many British people had heard “negative news” about food produced in the US as opposed to positive.

“Almost half of the poll responders (48%) are unaware of the USDA or its food safety programs,” the tender reads. “Just 1% of British consumers would buy American meat over British.”

UK media coverage about the hypothetical US-UK free trade deal has been framed around concerns over two big issues: Firstly, whether US health companies would get access to Britain’s NHS. And, secondly, how different food standards around the US agricultural industry could impact British farmers.