In the context of the input sentence, determine the relationship between 'Syriza' and 'Alexis Tsipras'.
Options: developer, chairperson, founded by, manufacturer

The new "preliminary draft" analysis of Greece's finances highlighted the deterioration that has taken place since Prime Minister Alexis Tsipras and his anti-austerity Syriza party took power at the beginning of 2015.
chairperson