LONDON — Beneath the pageantry, the angry protests and the Twitter tirades, President Donald Trump's state visit to the U.K. comes as the two nations are seeking to drastically reshape their relationship on trade.

The United Kingdom is — in theory at least — set to leave the European Union in October. For the United States, this rupture presents an unprecedented opportunity to strike a trade deal with its transatlantic partner.

The White House makes no secret that it sees Brexit as an opportunity to renegotiate the relationship in its favor: a chance to boost American jobs and economic growth.

In Britain, there are some who see a new U.S. deal as an essential pillar of a post-E.U. world, pivoting away from Brussels and toward Washington and the wider world.

But others here worry that the U.K. will become a global minnow when detached from the E.U. bloc, risking getting picked off by an American superpower that is uninterested in bilateral wins, only intent on competitive nationalism and putting "America first."

Trade deals are often years in the making. But there are two main themes that stir passions on this side of the pond: food standards and the publicly funded National Health Service.

Chlorinated chicken

As part of the E.U., Britain must follow strict standards for goods and services that apply across all 28 members of the union.

These standards are different to the U.S., and they mean that certain American goods cannot be sold in Britain because they don't pass these European regulations.

Assuming it does exit the E.U., the U.K. must decide which, if any, of these European standards to keep. The U.S. is clear that it wants the U.K. to stop "practices that unfairly decrease U.S. market access opportunities" and scrap regulations that "distort agricultural markets to the detriment" of the U.S., according to White House negotiating objectives released February.

Pro-American voices in the U.K. often tout the special relationship between London and Washington as an economic opportunity.

But there is a cost. In the U.S., chicken can be washed in chlorine and other chemicals, a practice supporters say kills bacteria. The E.U. doesn't allow this, not because chlorine is harmful, but because it says it allows lower welfare standards elsewhere in the production line. The same fear exists with beef produced with growth hormones.

Dispatches went undercover to reveal the worrying truth about the production of American chemically washed chicken.



US politicians want agriculture to be part of a post-Brexit trade deal, but there are worries it could lead to lower UK animal welfare and worker safety standards. pic.twitter.com/swbOUqsyiB — Channel 4 Dispatches (@C4Dispatches) June 3, 2019

"This would be a really, really big step backwards for us," said Ron Spellman, assistant general secretary of the Association of Meat Inspectors in Europe.

He was speaking with Britain's Channel 4 in response to a documentary airing this week that showed undercover footage at an American poultry factory.

NHS 'on the table'

There are few institutions that Brits take more pride in than the National Health Service. This is the publicly funded medical care that anyone living in the U.K. can access for free.

Although many grumble about long waiting times, and some do also carry private medical insurance, the popularity of the NHS is only rivaled by the armed forces and fire brigade.

It was unsurprising then that Woody Johnson, U.S. ambassador to the U.K., caused an uproar when he suggested on a Sunday political talk show that U.S. firms in the private sector should be able to bid for contracts in this public-sector darling.

There are also fears that the U.S. could force the NHS to pay more to big pharmaceutical companies for the costliest drugs, something the health organization is largely protected from at the moment. The White House trade objectives said it wanted to make sure these prices are"transparent," "nondiscriminatory" and provided "full market access for U.S.products."

Ambassador Johnson told the BBC's Andrew Marr Show that, like everything else, the NHS should be "on the table" when it comes to the trade deal between the two countries.

US Ambassador to the UK Woody Johnson tells #Marr that the whole of the economy, including the #NHS, will be “on the table” in a future US-UK trade deal after Brexit https://t.co/OakG0Gu6Ro pic.twitter.com/BlYJ9GKcuJ — BBC Politics (@BBCPolitics) June 2, 2019

This idea has been rejected by voices across the British political divide, with lawmakers keen to be seen as defenders of a venerated institution. Matt Hancock, health secretary and one of the contenders to replace Theresa May as prime minister, said he would rule it out if selected.

"I love our NHS. It’s been there for me and my family when we have needed it most, and I want to make sure it is always there for all families," he said on the same BBC show as Johnson. "So I have a clear message: The NHS is not for sale, and it will not be on the table in any future trade talks."

But critics fear that in a post-Brexit world the U.K. may be forced to make concessions in the face of a dominant American negotiating partner.

'Avoid at all costs'

May's eagerness to curry favor with the U.S. ahead of a trade deal could be seen in her rushing to Washington to congratulate Trump days after his inauguration in 2017.

Her successor will likely take a similar line; few championing the possibility of a prosperous post-Brexit Britain do not see the U.S. as part of the equation.

Critics say the president's "America first" doctrine seen in other trade negotiations around the world should be a signal that the U.K. deal would be hopelessly lopsided.

"The deal President Trump has in mind seems closer to an abusive relationship with a vulnerable country than a genuine partnership," wrote David Henig, the U.K. director of the European Centre For International Political Economy, a Brussels think tank.

"There are those this week who will rush to embrace the president's promises of a trade deal," Henig wrote for Politics.co.uk. "But any dispassionate assessment of his record over the last three years suggests we should avoid him at all costs."