As political parties busy themselves ahead of the April 16 referendum, the main opposition Republican People's Party (CHP) has decided to spearhead a "no" campaign, denouncing the constitutional amendment package and form indirect alliances with like-minded parties and NGOs, according to sources close to the CHP.

The CHP is the heaviest political player in the "no" camp, and strongly objects to the proposed constitutional amendments while favoring a strengthened executive role for Parliament instead.

Until April 16, the center-left CHP has the difficult task of keeping the "no" votes together, which comes from different political spectrums. Sources close to the CHP reported that the party's district and provincial bodies, as well as municipalities, siding with the "no" campaign, were ready to put joint efforts with other political parties, including the pro-PKK Peoples' Democratic Party (HDP), which also opposes the proposed changes to the constitution.

In addition, as part of the CHP's referendum campaign, it reportedly aims to woo "nationalist-conservative" voters, rather than its own center-left voter base, with special focus on Turkey's four main regions including the east, southeast, the Black Sea region and Central Anatolia.

Besides the pro-PKK HDP, the CHP is also looking to form alliances with the Felicity (Saadet) Party (SP) and the Homeland Party.

Though the CHP alliance with the "no-bloc" is not official, the party's headquarters reportedly gave directions to its local organizations and municipalities to establish the undercover alliance.