The party was rebuilt during the congress of Guidel and adopted democratic centralism. It also adopted a Marxist line and demanded in a modified version of its charter the abolition of capitalism and the collective appropriation of the means of production. At the same time, a UDB list won 11.5% of the votes in a local by-election in Auray, primarily thanks to the personality of its candidate Sten Kidna. In the 1971 local elections the UDB took part in the lists of the Union of the Left, except in Brest where it polled 4.8% running independently.