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.
In the context of the input sentence, determine the relationship between 'Syriza' and 'Alexis Tsipras'.
Options: currency, chairperson, employer, chief executive officer