An opinion poll suggests that former Greek Prime Minister Alexis Tsipras' leftist Syriza party will emerge as the biggest party after next month's election.
The poll indicates that this may occur without the sizeable margin it was hoping for, the first major opinion poll since he resigned last week has shown.
It indicates that almost two thirds of voters felt Mr Tsipras should not have sought a fresh mandate and that his favoured coalition ally would not make it into parliament.
That suggested his gamble to call early elections to consolidate his power base could backfire, though over a quarter of voters remained undecided, making the final outcome far from clear.
Syriza was suggested to be supported by 23% of those polled, with the conservative New Democracy party second on 19.5%, according to the survey, carried out by pollsters ProRata and published in today's Efimerida Ton Syntakton newspaper.
The previous ProRata poll in early July showed a wider gap in Syriza's favour, putting the party on 26% compared with 15% for New Democracy.
Mr Tsipras remained the most popular political leader with 41% of voters having a positive or very positive view, with New Democracy leader Vangelis Meimarakis was not far behind with 34%.
However, 64% of Greeks said they believed Mr Tsipras's move to call snap polls was wrong, while 68% agreed that Greece must stay in the eurozone at any cost, even if that meant further austerity.
"The answers to these two questions lead to the conclusion that early elections may cost the (former) prime minister and Syriza," the newspaper said.
A separate poll conducted by the University of Macedonia suggests Syriza would get 25% of the vote, compared to 22% for New Democracy.
The survey, conducted for Greek Skai TV, showed that Popular Unity would be backed by 5% of those polled.
A decree setting early elections for 20 September has been signed by President Prokopis Pavlopoulos
A caretaker government led by Supreme Court judge Vassiliki Thanou was sworn in earlier, comprising both technocrats and political figures.
The latter include George Chouliarakis, who was part of Greece's bailout negotiating team under Syriza, as interim finance minister.
An ally of the former deputy Prime Minister Yannis Dragasakis, Mr Chouliarakis took a decisive role in the talks in the summer and his appointment is likely to be seen as a positive for keeping the country's bailout programme on track.
Nikos Christodoulakis, who served as economy minister from 2001-2004 under the Socialist PASOK government, took the other key portfolio of economy, shipping, tourism and infrastructure.
Mr Tsipras abruptly resigned last week days after clinching an €86bn bailout package from European and International Monetary Fund lenders, hoping to crush a rebellion by far-left lawmakers and tighten his grip on power.
Popular Unity, the party formed last week by Syriza rebels who oppose the bailout, was backed by 3.5% in today's poll - above the 3% threshold needed to enter parliament.
However, the Independent Greeks, Mr Tsipras' former coalition partners, scored just 2%, meaning Syriza would be forced to seek another coalition partner.
