In the context of the input sentence, determine the relationship between 'Syriza' and 'Alexis Tsipras'.
Options: employer, operator, distributed by, chairperson

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
chairperson