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.

0905 : Far-left members of Greece's ruling Syriza party have revealed plans to form a splinter party, Popular Unity, following the resignation of Prime Minister Alexis Tsipras and calling of snap elections overnight.

Answer: chairperson