Alejandro Hope pointed out the following dramatic statistic:
PRI+PAN+PRD, porcentaje del voto nacional 1997: 90% 2015: 60%
That is quite a change! So what happened? I punched up the data on Mexican elections from 1997 to date and got the below time series for elections to the lower house of Congress:
Start with the heavy black line. It shows the three-party vote share for elections to the lower house of Congress. That share has been in sustained decline since 2006.
One explanation might be the fragmentation of the Mexican left. To adjust for that, I added back the vote share gained by the Labor Party (which effectively functions as an adjunct to the PRD) and Morena (which is a recent spinoff.) The trend remains.
So I then punched up the vote shares of each of the three major parties and got an interesting result: the PRD and PAN have been losing voters, while the PRI is generally maintaining. In other words, the smaller parties are cannibalizing the traditional right and left parties rather than Mexico’s traditional ruling party.
This is interesting. And it is not consistent with the idea that the fragmentation of the political system is a product of general disillusionment: that, presumably, should have hit the PRI as well, especially considering as its approval ratings are in the toilet.
What does that leave us? The following hypotheses come to mind:
- Voters are disillusioned, but the PRI has a particularly effective machine;
- Some other factor is causing smaller parties to proliferate and cannibalize the ends of the political spectrum.
Both of these might be true, of course. Or there may be a third. And hypothesis (2) is pretty vague. I have some thoughts on the matter, but first go read this.