A senior policy analyst at the Washington-based Cato Institute told Breitbart News one of the most certain turning points in the Brexit referendum campaign was the April 22 joint press conference with Prime Minister David Cameron and President Barack Obama, where Obama endorsed Cameron’s case for the United Kingdom staying in the European Union.

“It backfired massively,” said Marian Tupy, who is also the editor of Cato’s HumanProgress.org.

A reporter asked the president if the United States would be open to negotiating with a United Kingdom that had left the European Union.

“I think it’s fair to say that maybe some point down the line, there might be a UK-U.S. trade agreement, but it’s not going to happen anytime soon,” Obama said. “Our focus is in negotiating with a big bloc, the European Union, to get a trade agreement done, and the UK is going to be in the back of the queue.”

The British resent foreign leaders telling them what to do and how to conduct their lives, the economist said.

“It was exactly the wrong thing to say,” he said. “It was arrogant, ignorant and counter-productive–and Obama ought to be ashamed of himself.”

Because Obama used the British term “queue,” instead of the American phrasing: back of the line, Tupy said what was already heard by British voters as arrogant and threatening, also came off as contrived with most assuming the wording was handed to him as part of a script from Cameron. “In exchange for spending a lovely weekend with him and his family with the queen he had to deliver a backing of Cameron.”

Tupy said in the end, Brexit was the best choice for the United Kingdom and he fully expects other countries, such as the Netherlands, to leave as well.

Some of the richest countries in Europe, Switzerland, Norway and Luxembourg are not in the European Union and they are very prosperous, he said. “There are 6.5 billion people in the world that are not in the European Union. The UK can trade with them.”