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

Prime Minister Alexis Tsipras was heavily reliant on support from the Opposition in getting the vote to pass - following dissent from radical left hardliners within the governing Syriza party.
chairperson