Donald Trump may have just cost three countries, including the U.S., hosting rights to a major soccer tournament

This tweet from President Donald Trump may have just sunk the joint bid by the United States, Canada, and Mexico for the right to host the 2026 edition of the world's most prestigious men's soccer tournament, the FIFA World Cup:

The U.S. has put together a STRONG bid w/ Canada & Mexico for the 2026 World Cup. It would be a shame if countries that we always support were to lobby against the U.S. bid. Why should we be supporting these countries when they don’t support us (including at the United Nations)?

— Donald J. Trump (@realDonaldTrump) April 26, 2018

In other words, Trump, at least implicitly, threatened to revoke U.S. foreign aid from countries that intend to vote for Morocco's bid to host the 2026 World Cup over the joint USA/Canada/Mexico bid. Morocco, a country in northwestern Africa, was thought to be a heavy favorite to be selected to host the 2026 World Cup even before Trump's threatening tweet, and is probably even more of a favorite to be selected to host now.

According to USA Today, Trump's tweet appears to violate FIFA regulations prohibiting a head of government of a country that is either bidding to host or is part of a joint bid to host a World Cup:

FIFA's response on Friday was to point to its rule book, specifically restrictions on what government leaders cannot say in the build-up to the vote on June 13, when either the United bid, or the North African nation of Morocco, will emerge victorious.

“As a general rule, we cannot comment on specific statements in connection with the bidding process," FIFA said in a statement to Reuters. "We can only refer to the FIFA Regulations for the selection of the venue for the final competition of the 2026 FIFA World Cup, and in particular to the Bid Rules of Conduct incorporated therein.”

That rule, Section 9.1 (iv), states: "activities conducted by the Government (in case of a Single bid), or Governments (in case of a Joint bid) ... may adversely affect the integrity of the Bidding process and create an undue influence on the Bidding process."

In other words, don't flex your political muscles, either by promising or threatening to withhold support, in exchange for a vote.

Furthermore, it is possible, although highly unlikely, that FIFA could suspend the U.S. national soccer federation, which would prohibit the U.S. from being able to qualify a team for the 2019 FIFA Women's World Cup in France (the American men failed to qualify for the 2018 World Cup in Russia), even though the American women are the reigning Women's World Cup champions.