The PS party has advocated maintaining Slovakia's strong backing for Ukraine and would likely follow a liberal line within the European Union on issues such as majority voting to make the bloc more flexible, green policies and LGBTQ+ rights.
A government led by Fico and his SMER-SSD party would see the NATO member nation joining Hungary in challenging the European Union's consensus on support for Ukraine, just as the bloc looks to maintain unity in opposing Russia's invasion.
Fico's pro-Russian views reflect traditionally warm sentiments towards Moscow among many Slovaks, which have gathered strength on social media since the Ukraine war started.
Fico has pledged to end military supplies to Ukraine and to strive for peace talks - a line close to that of Hungary's leader Viktor Orban but rejected by Ukraine and its allies, who say this would only encourage Russia.
With no party projected to win an outright majority, forming a new government will hinge on results for more than half a dozen smaller parties, from libertarians to far-right extremists -- a scenario PS leader Michal Simecka underlined following the release of the exit polls.
"It will apparently be very close, between us and SMER, but also for those parties that may or may not get into parliament," Simecka said.
Progressive Slovakia was winning 23.5 per cent of the vote, ahead of 21.9 per cent for three-time prime minister Fico's SMER-SSD party, an exit poll by Focus agency for TV Markiza showed.
A second exit poll by Median agency for public broadcaster RTVS showed the liberal party winning 19.97 per cent of the vote, ahead of 19.09 per cent for Fico's party.
The incoming government in the nation of 5.5. million will take over a ballooning budget deficit forecast to be the highest in the euro zone.
Any coalition that PS could potentially form would likely need to include more right-wing or socially conservative parties, which would blunt its socially progressive and EU integration drive.
