The Parliament of Navarre was the devolved, unicameral legislature of the Chartered Community of Navarre, having legislative power in regional matters as defined by the Spanish Constitution and the Reintegration and Enhancement of the Foral Regime of Navarre Law, as well as the ability to vote confidence in or withdraw it from a President of the Foral Deputation. Voting was on the basis of universal suffrage, which comprised all nationals over eighteen, registered in Navarre and in full enjoyment of their political rights. The 50 members of the Parliament of Navarre were elected using the D'Hondt method and a closed list proportional representation, with a threshold of 3 percent of valid votes—which included blank ballots—being applied regionally. Parties not reaching the threshold were not taken into consideration for seat distribution. 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 Navarre. 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 Parliament of Navarre expired four years after the date of its previous election. The election Decree was required to be issued no later than the twenty-fifth day prior to the date of expiry of parliament and published on the following day in the Official Gazette of Navarre, with election day taking place between the fifty-fourth and the sixtieth day from publication. The previous election was held on 8 May 1983, which meant that the legislature's term would have expired on 8 May 1987. The election Decree was required to be published no later than 14 April 1987, with the election taking place no later than the sixtieth day from publication, setting the latest possible election date for the Parliament on Saturday, 13 June 1987. The Parliament of Navarre could not be dissolved before the date of expiry of parliament. In the event of an investiture process failing to elect a regional President within a two-month period from the first ballot, the candidate from the party with the highest number of seats was to be deemed automatically elected.
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 given poll. When available, seat projections are also displayed below the voting estimates in a smaller font. 26 seats were required for an absolute majority in the Parliament of Navarre.
Results
Aftermath
Investiture processes to elect the President of Navarre required for an absolute majority—more than half the votes cast—to be obtained in the first ballot. If unsuccessful, a new ballot would be held 48 hours later under the same majority requirement, with successive votes requiring only of a simple majority—more affirmative than negative votes—to succeed. If such majorities were not achieved, successive candidate proposals would be processed under the same procedure. In the event of the investiture process failing to elect a regional President within a two-month period from the first ballot, the candidate from the party with the highest number of seats was deemed to be automatically elected. As a result of the investiture process failing to provide a regional President within two months from the first ballot, Gabriel Urralburu was automatically elected on 30 September 1987 and officially sworn into office on 8 October.
