Under Germany's constitution, Merz needs a two-thirds majority to get the changes passed. With the support of the Greens and Social Democrats, he should succeed. Urgent motions by both the AfD and the Left to challenge next week's sessions of the outgoing parliament failed at the constitutional court on Friday, enabling the vote to go ahead.

Germany's chancellor-in-waiting and leader of the Christian Democratic Union party (CDU) Friedrich Merz speaks during an extraordinary meeting of the German Bundestag to discuss a €500-billion infrastructure fund and a revamp of borrowing rules aimed at modernizing the military and stimulating economic growth ahead of the formation of a new parliament at end of March,

German Chancellor-in-waiting Friedrich Merz said on Friday he had secured the crucial backing of the Greens for a massive increase in state borrowing, clearing the way for the outgoing parliament to approve the historic deal next week.