Refer to the input text as context and select the correct relationship between 'Syriza' and 'Alexis Tsipras' from the available options.
Options: director/manager, manufacturer, chairperson, employer

Greek Prime Minister Alexis Tsipras on Tuesday battled to hold his ruling Syriza party together as opposition mounted to a shocking new bailout deal that requires Athens to push through draconian reforms within two days.
chairperson