[26][27] Other parties and individual MEPs within the group support complete withdrawal from the block, referendums on EU membership and opposition to the Eurozone.

During the tenth European Parliament, the largest party in the group by number of MEPs is Brothers of Italy (FdI), followed by Polish Law and Justice (PiS).

[30] In June 2006, Cameron ordered Shadow Foreign Secretary William Hague to ensure the new group was created by 13 July 2006.

The Czech Civic Democratic Party (ODS) was part of MER but its leader, Mirek Topolánek, did not rule out staying in EPP-ED.

[35] Topolánek then attended the EPP Summit (a meeting of heads of state and government of the European People's Party) of 21 June 2007, adding speculation about the fragility of the new group.

[38] As the 2009 European elections approached, Cameron, Topolánek, and Conservative MEP Geoffrey Van Orden (a 'point-man' for the new group)[39] were looking for partners.

[40] People or parties that were rumoured to be possible partners in the new group included Law and Justice;[41][42][43] Lega Nord;[41][44] the Danish People's Party;[41][44] For Fatherland and Freedom,[40][41] Order and Justice,[41] the Pensioners' Party;[45] Order, Law and Justice;[39][46][47] Libertas;[48] Civic Union;[49] Electoral Action of Poles in Lithuania,[49] ChristianUnion-SGP;[50] the independent Indrek Tarand;[49] and Lijst Dedecker's Derk Jan Eppink;[41][42] from member states such as the Czech Republic,[51][52] Poland,[51][52] Italy,[51] Sweden,[51] the Baltic and Balkan states,[51] Belgium,[52] and the Netherlands.

Lajos Bokros, elected on the list of the Hungarian Democratic Forum (MDF) joined the group as the EPP did not want to accept him on pressure of the rival Fidesz.

The first election for the group leadership was also scheduled for 14 July 2009, pitting interim leader Kirkhope against fellow Briton Geoffrey Van Orden.

[61] On 15 December, rumours emerged that the eleven remaining PiS MEPs might leave the ECR and join the right-wing Europe of Freedom and Democracy (EFD) group instead.

Former interim leader Timothy Kirkhope was said to be the front runner,[63] but lost the election to Jan Zahradil of the Czech Republic's ODS.

[65] The May 2011 resignation of Silvana Koch-Mehrin, one of the fourteen Vice-Presidents of the European Parliament, led to the ECR considering putting another candidate forward to take the position they were denied through McMillan-Scott's defection.

[66] Conservative Party MEP Giles Chichester was nominated on 31 May, and was elected unopposed by the Parliament on 5 July 2011,[67] after the ALDE group to which Koch-Mehrin belongs failed to find a willing and suitable candidate.

On 26 December 2011, four members of United Poland – who had split from Law and Justice in November – left the ECR to join the Europe of Freedom and Democracy (EFD) group.

[79][80] Morten Messerschmidt, lead candidate for the Danish People's Party, was convicted in 2002 for publishing material that appeared to suggest that there is a link between a multiethnic society and rape, violence and forced marriages.

[81] Jussi Halla-aho, a Finns Party MEP, was convicted in 2012 after writing a 2008 blog entry which claimed that Islam "reveres paedophilia".

On 31 January 2020, the remaining British Conservative Party MEPs resigned from the group following the completion of the withdrawal of the United Kingdom from the European Union.

[98] After the election, the Alternative Democratic Reform Party of Luxembourg, the Cypriot National People's Front, the Homeland Movement, the Alliance for the Union of Romanians and the Romanian National Conservative Party were formally admitted into the group along with Reconquête (which had stood on a joint ticket with the Mouvement Conservateur) and the Denmark Democrats.

Reconquête's sole remaining MEP Sarah Knafo joined the new Europe of Sovereign Nations group instead while the former members stayed with the ECR.

[103][104] On 3 July 2024, Jaak Madison, an independent Estonian MEP who formerly was a member of the Conservative People's Party of Estonia, joined the ECR Group.

In a statement on Twitter, Vox leader Santiago Abascal expressed gratitude to the ECR group and said his party would continue to maintain strong relations with Meloni, but argued the move was a "historic opportunity to fight against a coalition of centre-right, socialist and far-left forces.

[112] On 31 August, Homeland Movement MEP Stephen Nikola Bartulica left the party, making him an independent member of the ECR.

Like the centre-right European People's Party (EPP), the founding members of the ECR mostly support pro-free market ideas with some of its MEPs maintaining ties to think-tanks such as The Cobden Centre and Open Europe,[117] as opposed to the more economic nationalist and anti-globalization approach of other euro-critical groups such as the EFDD and Identity and Democracy.