Greece’s Prime Minister Alexis Tsipras has resigned , hoping to strengthen his hold on power in snap elections after seven months in office in which he fought Greece’s creditors for a better bailout deal but had to cave in.Government officials said the aim was to hold the election on Sept. 20, with Tsipras seeking to crush a rebellion in his leftist Syriza party and seal public support for the bailout program, Greece’s third since 2010, that he negotiated.Faced with a near collapse of the Greek financial system which threatened the country’s future in the euro, Tsipras was forced to accept the creditors’ demands for yet more austerity and economic reform – the very policies he had promised to scrap when he was elected in January.