In the 1991–1992 transition to multiparty elections, UPADS was part of the National Alliance for Democracy (AND), which also included the Congolese Labour Party (PCT).

The Union for Democratic Renewal (URD) opposition coalition and the PCT were therefore successful in defeating Bongho-Nouarra's government in a no-confidence vote on 31 October 1992.

[1] Lissouba was ousted at the end of a civil war in 1997 and fled into exile, while Denis Sassou Nguesso of the PCT became president.

He alleged that five UPADS candidates, in Mossendjo, Moutamba, Nkayi, Mabombo and Dolisie electoral districts, had won but were deprived of victory in the results.

[15] In early October 2007, Tsaty-Mabiala said that UPADS would not participate in any national unity government because there had not been an agreement on resolving the country's problems.

It wanted a new and independent electoral commission, in addition to an "all-inclusive national dialogue" prior to the 2009 presidential election.

[20] However its candidacy was later rejected by the Contitutional Court on the ground that he had failed to establish his continuous residency in Congo-Brazzaville for at least two years.

[21] In the three following parliamentary elections, always under the leadership of Pascal Tsaty Mabiala, UPADS never managed to weaken PCT's absolute majority, remaining the main opposition force (tied with UDH-Yuki in 2017 and 2022) but always obtaining between 7 and 8 seats.