The European Union’s leaders are meeting in Brussels on Thursday to try and strike a deal with Prime Minister Viktor Orban of Hungary, who is blocking a multibillion euro fund aimed at securing Ukraine’s financing for the next few years.

Talks are gridlocked and the mood toward Mr. Orban is negative, with European leaders, unusually united against one of their peers, fed up with his stance on Ukraine and his anti-E.U. bluster.

What’s at stake?

A 50-billion euro ($54 billion) fund to support Ukraine through to the end of 2027.

Ukraine is facing one of is most difficult moments since Russia’s full-scale invasion nearly two years ago, with U.S. aid held up and virtually no progress on the battlefield.

Kyiv urgently needs fresh cash to keep basic services running. The E.U. aid, to be dispensed in the form of loans and grants over the next four years, would both cover immediate needs and allow Ukraine to plan its long-term budget.

This money is part of auxiliary funds, still under negotiation, to supplement the E.U. budget and pay for things like emergency responses to natural disasters. If there’s no deal over the funding for Ukraine, the other parts of the budget will also be held up.

There are broader issues at stake. If E.U. leaders fail to agree on long-term support for Ukraine, it could undermine the bloc’s credibility. And a definitive rupture over Ukraine could be hard to recover from, reinforcing Hungary’s isolation.