José Manuel Barroso (2004–2014)
José Manuel Barroso became president in 2004: the Parliament once again asserted itself in objecting to the proposed membership of the Barroso Commission. Owing to this opposition, Barroso was forced to reshuffle his College before taking office. The Barroso Commission was also the first full Commission since the enlargement in 2004 to 25 members; hence, the number of Commissioners at the end of the Prodi Commission had reached 30. As a result of the increase in the number of states, the Amsterdam Treaty triggered a reduction in the number of Commissioners to one per state, rather than two for the larger states.
Allegations of fraud and corruption were again raised in 2004 by former chief auditor Jules Muis. A Commission officer, Guido Strack, reported alleged fraud and abuses in his department in the years 2002–2004 to OLAF, and was fired as a result. In 2008, Paul van Buitenen (the former auditor known from the Santer Commission scandal) accused the European Anti-Fraud Office (OLAF) of a lack of independence and effectiveness. During Barroso's presidency of the Commission, EU accession negotiations began with Croatia and Turkey in 2005. While Croatia officially became a member in 2013, Turkey's accession process remains effectively suspended.
Barroso's first Commission term expired on 31 October 2009. Under the Treaty of Nice, the first Commission to be appointed after the number of member states reached 27 would have to be reduced to "less than the number of Member States". The exact number of Commissioners was to be decided by a unanimous vote of the European Council, and membership would rotate equally between member states. Following the accession of Romania and Bulgaria in January 2007, this clause took effect for the next Commission. The Treaty of Lisbon, which came into force on 1 December 2009, mandated a reduction of the number of Commissioners to two-thirds of member-states from 2014 unless the Council decided otherwise. Membership would rotate equally and no member state would have more than one Commissioner. However, the treaty was rejected by voters in Ireland in 2008 with one main concern being the loss of their Commissioner. Hence a guarantee given for a rerun of the vote was that the council would use its power to amend the number of Commissioners upwards. However, according to the treaties it still has to be fewer than the total number of members, thus it was proposed that the member state that does not get a Commissioner would get the post of High Representative – the so-called 26+1 formula. This guarantee (which may find its way into the next treaty amendment, probably in an accession treaty) contributed to the Irish approving the treaty in a second referendum in 2009.
Lisbon also combined the posts of European Commissioner for External Relations with the council's High Representative for the Common Foreign and Security Policy. This post, also a vice-president of the Commission, would chair the Council of the European Union's foreign affairs meetings as well as the commission's external relations duties. The treaty further provides that the most recent European elections should be "taken into account" when appointing the president of the European Commission, and although they are still proposed by the European Council; the European Parliament "elects" candidates to the office, rather than "approves" them as under the Treaty of Nice.
The Barroso Commission is, in reaction to Euroscepticism, said to have toned down enforcement to increase integration.