1991 Riojan regional election

The 1991 Riojan regional election was held on Sunday, 26 May 1991, to elect the 3rd General Deputation of the autonomous community of La Rioja. All 33 seats in the General Deputation were up for election. The election was held simultaneously with regional elections in twelve other autonomous communities and local elections all throughout Spain.

The ruling Spanish Socialist Workers' Party (PSOE) saw an increase in support and obtained 16 seats, one short of an overall majority. The newly founded People's Party (PP), whose leader Joaquín Espert had lost the regional government in 1990 to a motion of no confidence, won two additional seats compared to People's Alliance's results in 1987, for a total of 15. The Riojan Party (PR) was able to maintain its 2 seats after a convoluted legislature, while United Left remained 0.5 percentage points short of entering the General Deputation. The Democratic and Social Centre (CDS) did not reach the required 5% threshold either and lost all its seats.

As a result of the election, the incumbent PSOE–PR coalition, led by regional premier and PSOE leader José Ignacio Pérez Sáenz, was re-elected for a full term in office. This would be the last time that the PSOE would win a regional election and would be able to form a government in La Rioja until 2019.

Electoral system
The General Deputation of La Rioja was the devolved, unicameral legislature of the autonomous community of La Rioja, having legislative power in regional matters as defined by the Spanish Constitution and the Riojan Statute of Autonomy, as well as the ability to vote confidence in or withdraw it from a President of the Autonomous Community. Voting for the General Deputation was on the basis of universal suffrage, which comprised all nationals over 18 years of age, registered in La Rioja and in full enjoyment of their political rights.

The 33 members of the General Deputation of La Rioja were elected using the D'Hondt method and a closed list proportional representation, with an electoral threshold of five percent of valid votes—which included blank ballots—being applied regionally.

The electoral law provided that parties, federations, coalitions and groupings of electors were allowed to present lists of candidates. However, groupings of electors were required to secure the signature of at least 1 percent of the electors registered in La Rioja. Electors were barred from signing for more than one list of candidates. Concurrently, parties and federations intending to enter in coalition to take part jointly at an election were required to inform the relevant Electoral Commission within ten days of the election being called.

Election date
The term of the General Deputation of La Rioja expired four years after the date of its previous election. Legal amendments earlier in 1991 established that elections to the General Deputation were to be fixed for the fourth Sunday of May every four years. The previous election was held on 10 June 1987, setting the election date for the General Deputation on Sunday, 26 May 1991.

The General Deputation of La Rioja could not be dissolved before the date of expiry of parliament except in the event of an investiture process failing to elect a regional President within a two-month period from the first ballot. In such a case, the General Deputation was to be automatically dissolved and a snap election called, with elected deputies merely serving out what remained of their four-year terms.

Opinion polls
The table below lists voting intention estimates in reverse chronological order, showing the most recent first and using the dates when the survey fieldwork was done, as opposed to the date of publication. Where the fieldwork dates are unknown, the date of publication is given instead. The highest percentage figure in each polling survey is displayed with its background shaded in the leading party's colour. If a tie ensues, this is applied to the figures with the highest percentages. The "Lead" column on the right shows the percentage-point difference between the parties with the highest percentages in a poll. When available, seat projections determined by the polling organisations are displayed below (or in place of) the percentages in a smaller font; 17 seats were required for an absolute majority in the General Deputation of La Rioja.