Greece's Left Coalition called on Sunday for an anti-bailout coalition, saying the country's general election showed that austerity policies had been soundly defeated and a peaceful revolution ushered in.
The Communist KKE - which believes Greece should abandon the euro - immediately rejected Tsipras's call for a leftist alliance.
"Mrs Merkel needs to understand that austerity policies have suffered a huge defeat," said Left Coalition leader Alexis Tsipras, referring to German Chancellor Angela Merkel.
"With their vote, Greek people gave a mandate for a new dawn in our country with solidarity and justice instead of barbaric bailout measures."
Tsipras' party has emerged as the surprise star of the election and is on track to finish in second place with 16 percent of the vote, according to early results. The success comes at the expense of the big pro-bailout parties, New Democracy and PASOK, who were punished for backing austerity.
The KKE are projected to take about 8.5 percent of the vote.
"The parties which signed the bailouts without Greek people's consent are now a minority," Tsipras said.