One day Xavier Trias wins; the next, Jaume Collboni, and sometimes even Ada Colau. What is happening in Barcelona? Is it a city with a volatile electorate whose changing mood carries over into the polls? Or is it that the correlation is so close that it is not possible to clearly determine who will ultimately be the winner? The answer is a mixture of all these things, although the decisive factor is embodied in an electorate that has evolved towards fragmentation and that, increasingly, registers a very fickle voting intention.
History supports this interpretation, but the polls also offer some clues. For example, more than a third of voters plan to decide their vote in the period between the start of the electoral campaign and voting day. In fact, 5% will make that decision "on the same day of the elections." And, furthermore, currently only 16% always vote for the same party. More than 50% decide what they vote (or if they vote) "according to what is best for them at all times." The data is from the CIS.
From there it is understood how unpredictable the electoral outcome is when the campaign has not even started. But the case of Barcelona presents a specificity that can be appreciated more clearly from the historical evolution of the results. In 1979, in the first democratic municipal elections after the dictatorship, the difference in absolute vote between the first party (then the PSC) and the second party with the most votes (the PSUC) was close to 120,000 ballot papers and 15 percentage points. Translated into councillors, the Socialists added seven more councilors than the Eurocommunists.
The gap between the party with the most votes (PSC again) and the second force (now CiU) grew in the 1983 elections to over 165,000 votes (which translated into an advantage of almost twenty percentage points and eight councilors for the winner). The differences between the first and the second forces remained between 70,000 and 90,000 votes during the following two decades. The exception occurred in 1999, when the PSC's advantage over CiU once again exceeded 160,000 ballots (and was close to 24 percentage points).
Obviously, in the face of such correlations, the polling institutes did not find great difficulties in estimating a winner. Even so, elections as close as those between Pasqual Maragall and Miquel Roca in 1995 decided the color of the mayor's office by just one tenth: the figure that allowed Esquerra to enter the cast of councilors and tip the scales in favor of the bloc of left that made up PSC and ICV. Otherwise, CiU and Partido Popular would have added an absolute majority.
Even so, the forecasts continued to settle on clear differences until 2007. That year, the gap between Jordi Hereu and Xavier Trias fell to just over 25,000 ballots (and 4.5 percentage points). Only two councilors separated the first from the second force.
Since then, and although in 2011 the CiU prevailed over the PSC by a margin of almost 40,000 votes and three mayors, the correlation has only narrowed. And all this in parallel to a greater fragmentation of the electoral market: between 1979 and 2011, the formations with representation in the Consistory oscillated between four and five. But in 2015 the number rose to seven, and in 2019, to six.
The best reflection of that evolution is the current distance between the first and the second force. In 2015, the advantage of the winner (Barcelona en Comú) over the second classified (CiU) fell to just over 17,000 ballots, two and a half points and a lone mayor. And in 2019, the differences narrowed even more: less than 5,000 votes and six tenths of a percentage. A tie at 10 councilors and, for the first time, the most voted formation (then ERC) did not govern in Barcelona. But in light of these millimeter differences between the main forces of the Barcelona City Council, it is perfectly foreseeable that, if a similar correlation is maintained today, the winner's advantage will be almost undetectable.
