As a result of the legislative elections of 1989, the MPP won two seats in the Chamber of Deputies: Helios Sarthou (a Union lawyer) and Hugo Cores (PVP).

It has since become the largest faction within the Broad Front, the leftist coalition which won the elections in 2004 and took power in March 2005.

The MPP gained in votes, thus obtaining two seats in the Chamber of Deputies (José Mujica and Eleuterio Fernández Huidobro) and one in the Senate (Sarthou).

In the elections of that year, Mujica ran for the Senate and the turnout for the MPP was increased, giving the party two seats in the upper chamber.

The growth in popularity continued so that in 2004 the MPP got six seats in the Senate, and contributed to the victory of presidential candidate Tabaré Vázquez who then became the first left-wing president of the country.