Budapest made good on its threat to oppose 18 billion euros ($19 billion) of financial support for war-torn Ukraine at a meeting of EU finance ministers in Brussels.
The much-needed aid for Kyiv is one of several initiatives Budapest is stalling as it faces having 13 billion euros in EU funds for it frozen by the bloc over its failures on stopping graft and ensuring judicial independence.
Hungary is also vetoing a longstanding push for an EU-wide minimum corporate tax.
Orban's government has committed to undertaking a raft of reforms demanded by the EU, but has not satisfied Brussels that it is doing enough.
Some European diplomats pointed out that Hungarian lawmakers are meeting this week to pass more legislation that could bring it closer to meeting those reform targets.
Diplomats said the commission had been asked to provide an "update" on Hungary's reforms next week, in a possible sign a way out of the impasse was being forged.
EU member states have until December 19 to vote on whether to back, reject or change the commission recommendation.
The issue could drag on towards the deadline and be discussed by a December 15 summit of leaders in Brussels.