Take context from the input text and decide on the accurate relationship between 'Syriza' and 'Alexis Tsipras' from the options provided.
Options: chairperson, employer, currency, chief executive officer

The Syriza party of former Greek prime minister Alexis Tsipras -- which came to power in January on a pledge to renegotiate terms of their international bailout but ultimately had to cave to creditor demands -- has a wafer-thin lead in the polls over the conservative New Democracy.
chairperson