Utilize the input text as a context reference, choose the right relationship between 'Syriza' and 'Alexis Tsipras' from the options.
Options: chairperson, industry, manufacturer, owner of

Greek Prime Minister Alexis Tsipras on Wednesday had to face down a major mutiny in his radical left Syriza party, and violent protests in the streets of Athens, to win parliamentary approval for the draconian reforms demanded in the bailout package.
chairperson