Utilize the input text as a context reference, choose the right relationship between 'Syriza' and 'Alexis Tsipras' from the options.
Options: currency, chairperson, legal form, headquarters location

While the result is a victory for Prime Minister Alexis Tsipras in that he managed to convince parliament to back him on the bailout, he did suffer a major rebellion from Syriza MPs for the second time in a week -- prompting analysts to predict he may be forced to call early elections.
chairperson