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.
Refer to the input text as context and select the correct relationship between 'Syriza' and 'Alexis Tsipras' from the available options.
Options: currency, chief executive officer, chairperson, employer