BRUSSELS – A summit of the European Union’s 27 national leaders, charged with agreeing on a long-term budget for the bloc, broke up Friday without being able to reach a deal.

Coming just days after the 17 eurogroup finance ministers failed, yet again, to agree on the conditions for releasing badly needed bailout money for Greece, the failure of the two-day summit raises questions about how the bloc makes important decisions. In most cases, unanimity is required, meaning that each country wields veto power.

The prospect of failure had hung over the EU leaders’ summit, charged with agreeing on a long-term spending plan of around $1.25 trillion for the 27-country bloc. Some countries wanted the budget to rise, while others insisted it had to fall.