On 24 June, Turkey has concurrent presidential and assembly elections. These will usher in the new constitution, under which Turkey becomes a presidential system. (The current system is premier-presidential, having changed from parliamentary with the adoption of direct presidential elections.)
The election was called earlier than necessary in an attempt by the president, Recep Tayyip Erdogan, to catch the opposition unprepared. However, unexpectedly, several opposition parties have assembled
joint lists an alliance (see clarification below) to contest the assembly elections. Polling suggests that they could win a majority.
The coalition behavior of the opposition is unusual in that it features parties running in a pre-election coalition for assembly elections while running separately for a concurrent presidential election. I know of few cases of major parties behaving this way. It makes sense, however, in that Turkey’s 10% nationwide threshold for assembly seats makes for potentially high disproportionality (so much so that I questioned whether it was “democratic” several years before the crackdown that followed the attempted coup). On the other hand, the presidency is elected by two-round majority, meaning first-round divisions do not necessarily prevent a group of parties eventually getting one of their own elected. (See Chile 2005 for another example of such unusual alliance behavior.; also Taiwan 2012.)
Zeynep Somer-Topcu clarifies, regarding the assembly alliances:
Ballot had each party and then a larger box for the alliance. You could just stamp anywhere within the box for alliance (if no party preference). Threshold applies to alliance but each party’s MPs enter based on their parties’ vote shares once alliance passes threshold.
(via Twitter, presented here with her OK)
I think it is quite unusual for alliances to work this way, allowing vote pooling across separate lists to help drag smaller parties over a threshold.