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.

Greece's voters decisively rejected international creditors' tough bailout terms Sunday, but Greek premier and Syriza leader Alexis Tsipras insisted the result does not mean a "rupture" with Europe despite fears it will end in a "Grexit" from the eurozone.

Answer: chairperson