The Parliament of Andalusia was the devolved, unicameral legislature of the autonomous community of Andalusia, having legislative power in regional matters as defined by the Spanish Constitution of 1978 and the regional Statute of Autonomy, as well as the ability to vote confidence in or withdraw it from a regional president. Voting for the Parliament was on the basis of universal suffrage, which comprised all nationals over eighteen, registered in Andalusia and in full enjoyment of their political rights. The 109 members of the Parliament of Andalusia were elected using the D'Hondt method and a closed list proportional representation, with a threshold of three percent of valid votes—which included blank ballots—being applied in each constituency. Parties not reaching the threshold were not taken into consideration for seat distribution. Seats were allocated to constituencies, corresponding to the provinces of Almería, Cádiz, Córdoba, Granada, Huelva, Jaén, Málaga and Seville, with each being allocated an initial minimum of eight seats and the remaining 45 being distributed in proportion to their populations. The use of the D'Hondt method might result in a higher effective threshold, depending on the district magnitude. The electoral law allowed for parties and federations registered in the interior ministry, coalitions and groupings of electors to present lists of candidates. Parties and federations intending to form a coalition ahead of an election were required to inform the relevant Electoral Commission within ten days of the election call, whereas groupings of electors needed to secure the signature of at least one percent of the electorate in the constituencies for which they sought election, disallowing electors from signing for more than one list of candidates.
Election date
The term of the Parliament of Andalusia expired four years after the date of its previous election, unless it was dissolved earlier. Election day was to take place between the thirtieth and the sixtieth day from the date of expiry of parliament barring any date within from 1 July to 31 August. The previous election was held on 12 March 2000, which meant that the legislature's term would have expired on 12 March 2004. The election was required to take place no later than the sixtieth day from the date of expiry of parliament on the condition that it was not held between 1 July and 31 August, setting the latest possible election date for the Parliament on Tuesday, 11 May 2004. The president had the prerogative to dissolve the Parliament of Andalusia and call a snap election, provided that no motion of no confidence was in process and that dissolution did not occur before one year had elapsed since the previous one. 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. 55 seats were required for an absolute majority in the Parliament of Andalusia.
