In elections Saturday, the Taiwanese president, Ma Ying-jeou of the Kuomintang (KMT), was reelected with 51.8% of the vote. Tsai Ing-wen of the Democratic Progressive Party (DPP) came second with 45.6%, and James Soong of the People First Party won 2.8%.

The election is by plurality, so it was not especially close.

These were the first concurrent elections in Taiwan, the electoral cycle having been modified recently. As is to be expected with concurrent elections, the presidential and legislative votes were quite similar. The KMT-led alliance won 51.5% of the legislative votes, and will continue to control a majority of seats, with 67 of 113. (This is a decline from 85 at the previous, non-concurrent, election of 2008.)

These elections feature an unusual example of two parties competing in presidential elections but allied in concurrent legislative elections. Soong’s People First Party is part of the Pan Blue alliance, and whereas Sung himself managed only 2.8% of the vote, his party contributed 5.5% of the Pan Blue legislative vote.

Taiwan’s electoral system is mixed-member majoritarian (or parallel), with 79 district races decided by plurality, and 34 nationwide seats elected by proportional representation. People First won one single-seat contest, and 2 list seats. I assume the parties in alliance run common candidacies in the single-seat districts (and hence that the KMT stood down in the one contest won by the PFP, and the PFP did not contest many other districts), but that they run separate party lists. I hope someone can confirm that.

The only other case I know of where two parties competed in a presidential election but were allied in a concurrent legislative election would be Chile, 2005. At the time of the Chilean example of this sort of unusual alliance behavior, I remarked that the electoral rules of Chile made it advantageous for the parties to remain in their legislative alliance even after they chose to compete in the presidential race. In Chile, these rules are two-seat D’Hondt open lists. Taiwan’s MMM provides similar, if distinct, incentives to cooperate.

What is more surprising about the Taiwanese case is that by running separate presidential candidates, the alliance risked splitting the vote, given the use of plurality rule. In Chile, on the other hand, the presidency is elected through majority runoff. That Soong’s vote for president, where a split of the alliance vote was risky, was so much lower than his party’s legislative votes can be scored as a victory for Duverger.