The president delivered a veiled threat over Twitter Thursday to countries that don’t support his country’s joint bid to host the 2026 World Cup – a move that could be a breach of FIFA rules prohibiting political interference in the process.

Trump tweeted his support of the U.S.’s joint bid with Canada and Mexico to co-host the 2026 event, adding: “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)?”

Trump’s comment could potentially contravene the sport’s governing body’s rules that prohibit political interference in the bid process, although a FIFA spokesman told VICE News that the body’s protocols meant he could not comment on the matter.

“As a general rule, please understand we cannot comment on specific statements in connection with the bidding process,” said the spokesman.

Morocco is the only rival to the American joint bid to host the event. The winning candidate will be chosen by the 212 FIFA member associations in a vote on June 13 in Moscow, with each member given one vote each.

While the American bid can offer many advantages, including large high-quality stadiums and strong infrastructure, it is by no means assured to win, with strong backing expected for Morocco’s bid from countries in Africa and the Middle East. France and Russia have also said they’ll support Morocco’s bid.

But Morocco’s bid has faced allegations of political interference after a government minister on the Caribbean island of Dominica announced her country’s support for the North African country after meeting with a Moroccan diplomat.

Announcing her country’s backing for the Moroccan bid, Dominican Foreign Minister Francine Baron spoke of expanding Morocco’s support for her country, including through student scholarships ­– which may have been a breach of FIFA’s ban on votes being linked to development projects.

FIFA Secretary General Fatma Samoura wrote to member associations in January warning them about linking their vote “with other affairs or bidding processes unrelated to the merits of the submitted bids,” saying to do so would jeopardize the bidding process. The sport’s global governing body last month pledged to conduct a “fair, objective and transparent” bidding process after controversy surrounded the 2010 vote awarding the 2018 event to Russia and the 2022 edition to Qatar.