Belgian Prime Minister Charles Michel resigned just days after one of his main coalition partners left for migration.
Michel lost support from the New Flemish Alliance (N-VA) for a UN migration agreement in Marrakech, signed last week in Marrakech.
His move follows angry demonstrations in Brussels against the UN pact.
Mr. Michel has told King Philippe of his decision. The king has not yet announced whether he will accept the resignation.
Mr. Michel, 42, took office in October 201
He announced his intention to resign on Tuesday following a parliamentary debate in which opposition parties rejected calls to support his minority government.
While Belgium should vote next May, its decision now opens up the possibility of early elections.
Mr Michel had previously defended the Marrakech Migration Pact as it constituted an "opportunity for better European and international cooperation" -operation.
The non-binding agreement seeks an international migration approach that is "the sovereign rights of states reaffirming its "national" migration policy and asserting the "fundamental" importance of legal migration  Critics in Europe, however, believe that this will lead to increased immigration to the continent.
In July, 196 UN members voted the Global Compact for safe, orderly and regular migration.
The treaty was signed by 164 countries with the US and some European countries – including Austria, Hungary, Italy, Poland and Slovakia – refused to formally accept the agreement.
Thousands of demonstrators marched in Brussels this weekend el against the Parliament ct. The police used tear gas and water cannons when clashes erupted.
A counter-protest organized by leftist groups and charities in the city center attracted about 1,000 people.