Greece's main opposition Syriza, a coalition of the radical left, on Sunday re-elected its leader Alexis Tsipras and voted to make the party more efficient.
"Starting tomorrow, with our new party, all together, stronger and more united than ever, we will embark on our great and victorious path," Tsipras said in a statement issued by the party.
Tsipras, who ran against another two candidates, was re-elected with 74.08 percent of the votes.
At the end of a dramatic five-day party conference and heated debates, Syriza decided to adopt a new, unified form, abandoning its previous format that featured various small factions.
Syriza scored a surprising second place in parliament in the elections of June 2012, winning 72 seats out of an overall 300.
The party came right after conservative Prime Minister Antonis Samaras' New Democracy that won 129 seats, a number that has now dropped to 127.
Syriza gained great support after vowing to scrap Greece's bailout deal with the European Union and International Monetary Fund, which has put the indebted country on a harsh path of austerity.
The party's anti-bailout rhetoric caused widespread concern in Europe before last year's election.
Tsipras and Syriza have continued to firmly oppose the conservative-led, coalition government's austerity policies.
Speaking at the party conference on Saturday, Tsipras voiced support for municipal employees who are currently on strike protesting a redeployment plan.
"We are and will be with them to the end," he said.