Utilize the input text as a context reference, choose the right relationship between Syriza and Alexis Tsipras from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

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