The president of the Iraqi Kurdistan Region, Masoud Barzani, has renewed calls for Turkey to release Selahattin Demirtas, the co-leader of the Peoples’ Democratic Party (HDP), and other lawmakers from the pro-Kurdish bloc who are being held on a mind-numbing array of thinly supported terror charges.

Barzani made the appeal during an hour-long meeting Feb. 25 with President Recep Tayyip Erdogan in Istanbul, reported the Iraqi Kurdish Rudaw media organization. Barzani described his talks with Erdogan at the sumptuous Ottoman-era Mabeyn kiosk as “very good.” He said, “We discussed all subjects,” but chose not to elaborate.

Coming ahead of a referendum on expanding the powers of the Turkish presidency due to be held on April 16, the Iraqi Kurdish leader’s visit has sparked speculation that Erdogan hopes a halo effect will win him votes from conservative Kurds.

Barzani’s close ties with Erdogan remain a matter of controversy in Turkey and Iraqi Kurdistan alike. Turkish Kurds who identify with imprisoned Kurdistan Workers Party (PKK) leader Abdullah Ocalan resent Barzani’s cooperation with the Turkish government and there is escalating pressure on the HDP and its sister party, the Democratic Regions Party (DPB), since the breakdown of a two-and-a-half-year cease-fire between the PKK and the state in July 2015.