Take context from the input text and decide on the accurate relationship between 'Syriza' and 'Alexis Tsipras' from the options provided.
Options: platform, brand, position held, chairperson

In Athens, Prime Minister Alexis Tsipras and his inner circle debated whether to take on anti-bailout rebels within his own radical left Syriza party by calling a parliamentary confidence vote or to go straight to early elections.
chairperson