On 1 May 2004 ten new member states joined the European Union. This article describes the party affiliations of the leaders of each member-state represented in the European Council from 1 May until the end of 2004. The list below gives the political party that each head of government, or head of state, belonged to at the national level, as well as the European political alliance to which that national party belonged. The states are listed from most to least populous. More populous states have greater influence in the council, in accordance with the system of Qualified Majority Voting.
__TOC__
| Party | 1 May 2004 | 12 July 2004 | 1 November 2004 | 2 December 2004 | 3 December 2004 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| QMVa | QMVa | QMVb | QMVb | QMVb | |||||||
| Party of European Socialists | 7 | 50 | 7 | 50 | 7 | 146 | 7 | 146 | 7 | 146 | |
| European People's Party | 10 | 49 | 10 | 49 | 10 | 123 | 11 | 127 | 12 | 131 | |
| European Liberal Democrat and Reform Party | 5 | 17 | 4 | 14 | 4 | 30 | 4 | 30 | 3 | 26 | |
| Alliance for Europe of the Nations | 1 | 3 | 1 | 3 | 1 | 7 | 1 | 7 | 1 | 7 | |
| European Green Party | 1 | 3 | 1 | 3 | 1 | 4 | 0 | 0 | 0 | 0 | |
| Independent | 1 | 2 | 2 | 5 | 2 | 11 | 2 | 11 | 2 | 11 | |
a – Transitional QMV system with 124 total votes and a qualified majority of 88 (70.97%), in use until 1 November 2004.
b – Final EU-25 QMV system with 321 total votes and a qualified majority of 232 (72.27%).
| Member-state | Votes | Leader | National party | European party | ||
|---|---|---|---|---|---|---|
| a | b | |||||
| Germany | 10 | 29 | Gerhard Schröder | SPD | PES | |
| United Kingdom | 10 | 29 | Tony Blair | Lab | PES | |
| France | 10 | 29 | Jacques Chirac | UMP | EPP | |
| Italy | 10 | 29 | Silvio Berlusconi | FI | EPP | |
| Spain | 8 | 27 | José Luis Rodríguez Zapatero | PSOE | PES | |
| Poland | 8 | 27 | Leszek Miller | SLD | PES | |
| Netherlands | 5 | 13 | Jan Peter Balkenende | CDA | EPP | |
| Greece | 5 | 12 | Kostas Karamanlis | ND | EPP | |
| Czech Republic | 5 | 12 | Vladimír Špidla | ČSSD | PES | |
| Belgium | 5 | 12 | Guy Verhofstadt | VLD | ELDR | |
| Hungary | 5 | 12 | Péter Medgyessy | MSZP | PES | |
| Portugal | 5 | 12 | José Manuel Barroso | PPD/PSD | EPP | |
| Sweden | 4 | 10 | Göran Persson | SAP | PES | |
| Austria | 4 | 10 | Wolfgang Schüssel | ÖVP | EPP | |
| Slovakia | 3 | 7 | Mikuláš Dzurinda | SDKÚ | EPP | |
| Denmark | 3 | 7 | Anders Fogh Rasmussen | V | ELDR | |
| Finland | 3 | 7 | Matti Vanhanen | Kesk. | ELDR | |
| Ireland | 3 | 7 | Bertie Ahern | FF | AEN | |
| Lithuania | 3 | 7 | Artūras Paulauskas | NS | ELDR | |
| Latvia | 3 | 4 | Indulis Emsis | LZP | EGP | |
| Slovenia | 3 | 4 | Anton Rop | LDS | ELDR | |
| Estonia | 3 | 4 | Juhan Parts | RP | EPP | |
| Cyprus | 2 | 4 | Tassos Papadopoulos | DIKO | Independent | |
| Luxembourg | 2 | 4 | Jean-Claude Juncker | CSV | EPP | |
| Malta | 2 | 3 | Lawrence Gonzi | PN | EPP | |
DIKO's MEP joined the Alliance of Liberals and Democrats for Europe group in the European Parliament, but the party is not formally attached to any pan-European organization.
| Date | Member-state | Leader | National party | European party | |
| 12 July | Lithuania | Valdas Adamkus | Independent | ||
| 2 December | Latvia | Aigars Kalvītis | TP | EPP | |
| 3 December | Slovenia | Janez Janša | SDS | EPP | |
| Date | Member-state | Leader | National party | European party | |
| 2 May | Poland | Marek Belka | SLD | PES | |
| 17 July | Portugal | Pedro Santana Lopes | PPD/PSD | EPP | |
| 4 August | Czech Republic | Stanislav Gross | ČSSD | PES | |
| 29 September | Hungary | Ferenc Gyurcsány | MSZP | PES |