ATHENS (Reuters) - Rebels angered by Greece's international bailout walked out of the leftist Syriza party on Friday, formalising a widely-expected split after leader Alexis Tsipras resigned as prime minister to pave the way for early elections.
What is the relationship between 'Syriza' and 'Alexis Tsipras' in the context of the input sentence.
Options: chairperson, operator, platform, legal form