President Donald Trump had already embroiled himself in controversy even before he set foot on British soil for a three-day state visit to the United Kingdom on Monday.

Trump called London Mayor Sadiq Khan a “stone cold loser” on Twitter Monday morning, and then compared Kahn to presidential contender and New York City Mayor Bill de Blasio, who he said is “dumb and incompetent.”

“Kahn reminds me very much of our very dumb and incompetent Mayor of NYC, de Blasio, who has also done a terrible job - only half his height,” Trump wrote on Twitter.

So set the stage for what has already proven to be an unorthodox trip for a sitting U.S. president in England. Breaking with tradition, the president has not been invited to address the British House of Commons nor was he invited to stay in Buckingham Palace. The palace says they could not host Trump due to ongoing renovations.

Upon arrival, Trump was greeted by, according to The Washington Post’s estimate, tens of thousands of protesters, some of whom paraded through London with a 20-foot blimp featuring a cartoonish depiction of Trump in nothing but a diaper.

Weeks before, the U.K. was surprised by the announcement that Prime Minister Theresa May will resign on Friday. Speculation has amounted about who will step in to be the next prime minister. To WGBH News Analyst and CEO of the GroundTruth Project, Charlie Sennott, however, the answer is clear.

“It’ll be Boris [Johnson],” Sennott said during an interview with Boston Public Radio on Friday. Johnson is the former Secretary of State for Foreign and Commonwealth Affairs and was one of the most vocal backers of Brexit.

The trouble with Johnson, Sennott believes, is that he will face the same predicament as May. Despite three attempts, conservative members of parliament refused to ratify a European Union approved deal to transition the U.K. out, saying that the deal still left too much influence in the EU’s control. Sennott said that even with Johnson in power, hardliners are unlikely to accept any deal that is agreeable to the E.U.

“I don’t see how Boris Johnson, as foppish and talented as he is, how he’s going to possibly get this through ... How’s it going to be any different if it’s May or if it’s Boris?” Sennott said.

Behind the pageantry of the state visit and the political turmoil in Parliament, for Trump, the visit is an unprecedented opportunity to negotiate a new trade deal between the U.S. and U.K. Two issues that have stuck out to the administration are agriculture and healthcare.

On Sunday, Woody Johnson, the American ambassador to the U.K., told the BBC that the administration would be interested in opening up the British National Health Services to American products, a statement that was met with swift opposition from several members of Parliament.

“I have a clear message: The NHS is not for sale, and it will not be on the table in any future trade talks,” British health secretary Matt Hancock told the BBC in response to Johnson’s statement.

The administration’s desires to increase importation of American meat products into the U.K. also drew ire. Previously, American meat exports were not up to E.U. standards for importation, but with a new deal, Trump is now pushing for the U.K. to adopt America’s looser standards for cleansing meat, which allow chemicals like chlorine to be used in the process.

“We know that Brexit is all downsides. It is often called an act of national self-harm, but letting in chlorine-washed chicken as Woody demands would be literally harmful to the health of the nation. It makes me sick, in so many bloody ways,” Jay Rayner, a food critic and journalist who frequently writes for The Guardian, wrote on Twitter in March when Johnson first proposed the idea.

With all of the excitement and drama of a new trade deal, Sennott said that the Trump administration should dampen their hopes. Given all of the political tumult in the U.K since Brexit, and the very real possibility that a hard break from the E.U. could have dramatic economic consequences with global ramifications, he said a second Brexit referendum might now be on the table.

“I am just a firm believer in the idea the British are ultimately rational,” Sennott said. “They use common sense, they kind of like to pull up their socks and go on, and that’s why I think we’re going to have a second referendum.”