Refer to the input text as context and select the correct relationship between 'Syriza' and 'Alexis Tsipras' from the available options.
Options: chairperson, subsidiary, legal form, manufacturer

ATHENS (Reuters) - Greek Prime Minister Alexis Tsipras contained a rebellion in his left-wing Syriza party to win parliamentary approval on Thursday for a second package of reforms required to start talks on a financial rescue deal.
chairperson