The EU was built for six members. Its institutions — Commission size, Parliament composition, Council voting weights — were designed accordingly. They were stretched to fit nine, then twelve, then fifteen, and are now straining at twenty-seven. The decision to open accession negotiations with Ukraine and Moldova in 2024, together with the unfinished business of the Western Balkans, has reopened a debate member states spent two decades sidestepping. Can the EU get bigger without changing how it decides things? By 2026, the answer is plain. It cannot.

Qualified majority voting in the Council currently needs 55 percent of member states representing at least 65 percent of the EU population. At twenty-seven, that threshold is already hard to reach on contested issues. Add three or more members and building majorities on anything touching national sovereignty becomes practically impossible. Worse, the policy areas still governed by unanimity — foreign policy, taxation, enlargement, treaty revision — would freeze solid with extra veto players. Ukraine would arrive as a large, strategically important member with its own regional interests and historical grievances. Its presence in a unanimity-based foreign policy system would complicate decisions far beyond the Russia war.

Donald Trump's return to the White House in January 2025 has sharpened the QMV debate. The EU's sluggish, fractured response on Ukraine support, arms procurement, and sanctions has been blamed partly on Hungary's repeated vetoes. Kaja Kallas and Ursula von der Leyen have both backed QMV for specific foreign policy areas, including sanctions and human rights positions. France used to resist this, treating majority voting as an assault on national diplomatic sovereignty. The geopolitical climate of 2025-2026 has softened that stance. In early 2026 Macron said publicly that 'the alternative to majority voting is not national sovereignty but European irrelevance.'

The historical irony is thick. France was the original architect of the Luxembourg Compromise in 1966, which entrenched the de facto veto power that unanimity still provides. De Gaulle insisted that vital national interests could not be overridden by majority vote. Sixty years later, his successors face a world in which the veto is used not to protect French interests but to block EU responses to Russian aggression at the behest of a Hungarian government that Paris regards with open contempt. The contradiction between France's rhetorical commitment to European strategic autonomy and its institutional defence of the veto has become impossible to ignore.

Smaller member states have their own objections, and they are not trivial. Estonia, Latvia, and Lithuania worry that QMV in foreign policy would allow large states to override their security concerns. They remember 1939 and do not trust that Berlin or Paris will always align with their interests. These fears are genuine and deserve accommodation. The solution proposed by several legal scholars — a bicameral or weighted system for foreign policy QMV that protects the voice of small states while removing individual vetoes — has not yet gained political traction. The Commission's February 2026 communication on institutional reform mentioned it only in a footnote.

The economic governance dimension is equally pressing. Taxation remains unanimity-governed, which has made common corporate tax base negotiations a decade-long farce. Ireland, Luxembourg, and the Netherlands have each used their veto to protect competitive advantages that cost other member states billions in lost revenue. Enlargement would add new low-tax jurisdictions and new veto players to a system that has already failed to harmonise even the most basic tax avoidance rules. The political will to move to QMV on taxation exists in Paris and Berlin, but not in Dublin or Luxembourg, and the unanimity rule gives them an absolute veto.

The Convention on the Future of Europe, relaunched in 2025, was supposed to break this deadlock. It has not. After eighteen months of deliberation, the convention has produced a laundry list of desirable reforms — QMV expansion, streamlined Commission composition, revised Parliament seat allocation — but no agreed mechanism for achieving them. The problem is circular: the convention's recommendations require unanimous ratification, and the same governments that block QMV in the Council will block the treaty changes needed to introduce it. The convention has become a forum for stating the obvious rather than a pathway to action.

Public opinion, often invoked by reformers as a potential lever, offers mixed signals. Eurobarometer surveys consistently show majority support for more efficient EU decision-making, but the abstract question elides the concrete trade-offs. When voters in Ireland or the Netherlands are asked whether they would accept majority voting on taxation, support drops below 30 percent. The gap between generalised frustration with EU paralysis and specific willingness to cede national veto power is wide, and populist parties on both left and right have exploited it effectively. Reform requires not just institutional engineering but sustained political persuasion that no European leader has yet attempted.

Reform is still blocked by the need for unanimous consent to change the treaties. Any move from unanimity to QMV in new areas requires revision under Article 48 TEU, ratified by every member state. Hungary, Poland under its current government, and smaller states afraid of being outvoted by the large ones have said they will not ratify. The fallback is a 'multi-speed Europe' where willing members integrate more deeply through enhanced cooperation. That risks splitting the Union into concentric circles. By 2026, one thing is obvious: enlargement and institutional reform are not separate questions. They are the same question, and the EU cannot solve one without solving the other.