The UdC is a member of the European People's Party (EPP) and the Centrist Democrat International (CDI), of which Casini was president from 2004 to 2015.

In 2008 the party was the driving force behind the "Union of the Centre" (UdC), an alliance comprising, among others, The Rose for Italy of Bruno Tabacci and Savino Pezzotta, the Populars of Ciriaco De Mita and the Liberal Clubs of Ferdinando Adornato.

In December 2016 the UdC left the alliance, did not join Paolo Gentiloni's government and suffered the final split by Casini and his followers.

In the 2001 Italian general election, the Christian Democratic Centre (CCD), led by Pier Ferdinando Casini, and the United Christian Democrats (CDU), a 1995 split from the Italian People's Party (PPI) led by Rocco Buttiglione were part of the winning centre-right House of Freedoms coalition, but their joint list (informally known as White Flower) won a mere 3.2% of the vote (−2.6pp from 1996).

In the event, the two parties suffered the competition of European Democracy (DE), led by Sergio D'Antoni and formed largely by further splinters from the PPI, which obtained 2.4% of the vote.

Consequently, the party successfully lobbied for Follini's appointment as Deputy Prime Minister in Berlusconi's government with the goal of strengthening and balancing the coalition, while diminishing the influence of Lega Nord.

A fifth major split happened at the end of January 2008 when Bruno Tabacci and Mario Baccini left the party because Casini seemed eager to re-join Berlusconi for the upcoming election, after that the Prodi II Cabinet had not passed through a vote of confidence.

Shortly afterwards, when Casini refused to merge his party into Berlusconi's then-new political movement, The People of Freedom (PdL), the UDC was joined by The Rose for Italy of Tabacci, Baccini and Savino Pezzotta, as well as by two leading members of Forza Italia (FI), Ferdinando Adornato and Angelo Sanza.

In 2012 the UdC suffered the split of another Sicilian-based group, Cantiere Popolare (CP), which would be a strong competitor for the party in Sicily, along with the evergreen MpA.

[29] The UdC ran in the 2014 European Parliament election on a joint list with the New Centre-Right (NCD), a mainly Christian-democratic outfit emerged from a split from the PdL in its final days.

Additionally, while still being part of the government and AP, the UdC chose not to support the "yes" in the 2016 constitutional referendum and to distance from the NCD, rejecting any notion of a joint party.

[32][33] After the referendum, which saw a huge defeat of the "yes" side, the UdC left AP altogether, but, other than Casini and D'Alia, the party lost another deputy and, more important, minister Galletti.

[42] The decision led some leading former UdC members in Sicily to return into the party's fold, but was criticised by the party's deputy secretary Giuseppe De Mita,[43] his uncle Ciriaco and Follini, who would jointly launch Italy Is Popular,[44][45] lead it into the Popular Civic List and join the centre-left coalition.

[47] Thus, the UdC joined Us with Italy (NcI),[48][49][50] a pro-Berlusconi centrist electoral list formed by AP splinters (two groups, a Christian-democratic one led by Maurizio Lupi and a liberal one led by Enrico Costa), Direction Italy (DI), Civic Choice (SC), Act!, CP and the MpA,[51][52][53] with the goal of reaching 3%, required to win seats from proportional lists under a new electoral law.

Moreover, it wrote that many UDC members are "diehard corporatists who [...] get most of their votes from the south, where many households depend either on welfare or on public-sector employment".

The party's leading figure, Pier Ferdinando Casini, was critical of Silvio Berlusconi's leadership over the Italian centre-right and presented himself as a moderate alternative to populism, which, in his view, denoted the alliance between The People of Freedom (PdL) and Lega Nord.

This "centrist option" has not succeeded yet: the UdC has remained a much lighter force compared to Berlusconi's parties (Forza Italia, the PdL and finally the new Forza Italia), which have drawn most former DC voters, and Italians like confrontational politics based on alternative coalitions and many would support a two-party system, in place of the typically Italian fragmented political spectrum.

Moreover, although UdC members are keen on presenting themselves as moderates, their solid social conservatism has harmed their prospects, while FI/PdL/FI has been popular also among secularised middle-class voters.

[63] On specific issues, it is relevant to state that the UdC is one of the main supporters of nuclear energy in the Italian political arena.