In a tweet, the youth wing of the New Flemish Alliance (N-VA), Jong N-VA, said Trump could have the French-speaking region of southern Belgium for one euro.
Donald Trump may have been spurned in his approach to buy Greenland from Denmark, but the U.S. president may be consoled by an offer from Flemish nationalists to sell him Wallonia.
In a tweet, the youth wing of the New Flemish Alliance (N-VA), Jong N-VA, said Trump could have the French-speaking region of southern Belgium for one euro.
A picture accompanying the tweet showed Trump Tower looming over the Walloon city of Durbuy, mimicking the president's own image of one of his buildings in Greenland.
The tweet has already attracted considerable anger from Belgium's Walloons, but the president of Jong N-VA, Lawrence Vancraeyenest, told Euronews that it was meant as a joke.
"It was just a joke aimed at a young Flemish audience, going along with something trending on twitter, nothing more," he said.
"I sincerely hope there is still room for some humour in politics. Especially young people need that."
A Dutch-speaking region of Belgium, Flanders makes up 68% of the country's population, and has seen a surge in nationalist and separatist Flemish parties in recent years.
The N-VA won 43 seats in Belgium's 150-seat parliament in the latest elections, and in August entered talks with other Flemish parties to form a government after months of political stalemate.
Vancraeyenest said that the tweet was not intended to "make forming a federal government any more difficult" or "a political statement towards the government negotiations". He added that the anger from Walloons was "proof we each live in a different culture."
While Flanders has seen a surge on the right, Wallonia has gone the other way, with huge support for leftist parties in the last election.
The results prompted N-VA leader Bart De Wever to comment: "The difference between Flanders and Wallonia has never been so great."
The split between Flemish and Walloon parties typically leads to long delays in forming a coalition in Belgium. In 2010, it took parties 535 days, a record, to agree to a compromise and form a government.
Steve Detry, president of the youth wing of the Reformist Movement in Woluwe-Saint-Lambert, was one of dozens of critics of the tweet on Wednesday, saying that he found the joke "rude" and stupid".