What is the relationship between Syriza and Alexis Tsipras in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

Greece is set to receive the first instalment of its third multi-billion-euro bailout, as Prime Minister Alexis Tsipras mulls whether to hold early elections after the austerity bailout split his radical left Syriza party

Answer: chairperson