Setting aside their differences to combat the threat of Turkey becoming an Islamic state.

From the [1] BBC, with thanks to Davida:

Two secularist opposition parties in Turkey are joining forces to challenge the Islamist-rooted ruling AK Party in the July general election.

The alliance was announced at a news conference on Thursday by the Republican People's Party (CHP) and Democratic Left Party (DSP).

The 22 July election was brought forward from November to try to resolve a dispute over the Turkish presidency.

Secularists accuse the AKP of trying to pursue an Islamist agenda.