The party, which was officially launched in 1978, emerged from an opinion movement which arose in Trieste after the Treaty of Osimo was negotiated by Italy and Yugoslavia in 1975.

A local committee collected more than 65,000 signatures in order to stop the ratification of it by the Italian Parliament, which however eventually approved it in 1977.

[1] In the 1978 regional election the party, which considers itself "the first civic list in Italy", won 6.5% of the vote and four regional deputies, while Manlio Cecovini was appointed mayor of Trieste, after a strong showing of the party in the municipal election (27.5%).

[2][3] Some days later Manlio Cecovini (mayor of Trieste, 1978–1983) was elected to the European Parliament for the Italian Liberal Party.

Despite this, LpT continues to exist as a minor ally of Forza Italia in Trieste.