[13] While maintaining those traits, during the second half of the 20th century the party moved towards the centre on the left–right political spectrum, becoming increasingly economically liberal.

The PRI, whose power base was limited to Romagna, Umbria, Marche, the Tuscan littoral and Lazio, all but Tuscany former Papal States territories, was officially founded in 1895.

At the outbreak of World War I, the PRI sided with interventionists, aiming at supporting France (considered the motherland of human rights) and annexing Trento and Trieste (then part of Austria-Hungary).

In late 1946, Ugo La Malfa and Ferruccio Parri, formerly members of the Action Party (PdA), moved to the PRI.

Carlo Sforza, a Republican, was Minister of Foreign Affairs in the De Gasperi III Cabinet, although only as an independent.

Sforza signed the treaty of peace and contributed to the entrance of Italy into the Marshall Plan, NATO and the Council of Europe.

The exclusion of left-wing parties from the government in 1947 led the PRI to join the De Gasperi IV Cabinet.

As the PCI became ever closer to the Communist Party of the Soviet Union, Pacciardi later changed his mind and became Deputy Prime Minister.

Pacciardi, who had voted against, was expelled and founded a separate movement, Democratic Union for the New Republic (UDNR), whose electoral result were disappointing and whose members had largely returned to the PRI by the late 1960s (although Pacciardi, who received much criticism at this time for his association with coup plotters and neo-fascists, did not come back until after the UDNR was disbanded in 1980).

The attempt failed and a new government led by Giulio Andreotti was formed, with La Malfa as Deputy Prime Minister, but he suddenly died five days later.

The following twelve years, first under Spadolini and then under La Malfa's son Giorgio, saw the PRI as a stable member of the so-called Pentapartito, an alliance between the DC, the PSI, the PRI, the Italian Liberal Party (PLI) and the Italian Democratic Socialist Party (PSDI) which governed Italy from 1983 to 1991.

Under Spadolini, an urgent decree outlawing all secret lodges, such as Propaganda Due (which included numerous members of previous governments and of military forces), was approved.

The Spadolini II Cabinet fell in November 1983 due to a strife between Beniamino Andreatta (DC) and Rino Formica, Ministers of the Treasury and Finances respectively.

The party was divided in three groups: one led by Giorgio La Malfa joined the Pact for Italy, a second one led by Luciana Sbarbati joined Democratic Alliance (AD) and a third group left the party and formed Republican Left (SR).

[16] Many Republicans, including Jas Gawronski, Guglielmo Castagnetti, Alberto Zorzoli, Luigi Casero, Denis Verdini, Piergiorgio Massidda and Mario Pescante, left the PRI in order to join Forza Italia.

The Republicans were very disappointed by the five years of government of the centre-left and soon became critical supporters of the Prodi I Cabinet as part of The Clover, a centrist parliamentary alliance with the Italian Democratic Socialists (SDI) and the Union for the Republic (UpR).

[22][23] Another split loomed when La Malfa voted against the Berlusconi IV Cabinet and was suspended from the party in December 2010.

[29] He was replaced by two successive coordinators, Saverio Collura (from March 2014, when Nucara was contextually elected president, to December 2015) and Corrado Saponaro (from January 2016).

[39] In the 2020 Marche regional election, the PRI allied with the centre-right; this caused the European Republicans Movement to again split away from the Party to pursue an alliance with the centre-left.

[41][42][43] On the occasion of the 2022 Italian general election, the PRI, after having joined Civic Commitment (an electoral list led by Luigi Di Maio within the centre-left coalition)[44] for a few days, joined forces with the Action – Italia Viva, which ran outside the two main electoral coalitions.

However, at the 1900 Italian general election the PRI won 4.3% of the vote (7.3% in Lombardy, 9.6% in Emilia-Romagna, 15.0% in the Marche, 9.6% in Umbria and 7.2% in Apulia) and 29 seats from several regions of Italy, including also Veneto and Sicily, where they had some local strongholds.

[48] At the 1946 Italian general election, despite competition from the Action Party, which had a similar constituency and regional base, the PRI won 4.4% of the vote, with peaks in its traditional strongholds: around 21% in Romagna (32.5% in Forlì and 37.3% in Ravenna), 16.4% in the Marche (26.6% in Ancona and 32.9% in Jesi), 11.0% in Umbria and 15.2% in Lazio.

[50] In the 1970s, under the leadership of Giovanni Spadolini the Republicans gained support among educated middle-class voters, losing some ground in their traditional strongholds, but also increasing their share of vote elsewhere, notably in Piedmont, Lombardy and Liguria, where they became a strong competitor to the Italian Liberal Party for the votes of entrepreneurs and professionals.

This led to a gradual recovery in the party's fortunes, which reached their highest peak at the 1983 Italian general election.

Spadolini had been Prime Minister of Italy for two years by this point, and the party enjoyed a bounce which led it to the 5.1% of the vote.

[50] With the end of the First Republic, the party was severely diminished in term of votes and retreated to its traditional strongholds and in the South.