BRATISLAVA -- Slovak nationalist left government candidate Peter Pellegrini was on course to win the country's presidential election, results from most voting districts as well as projections showed on Saturday.

A Pellegrini win would be a boost for Prime Minister Robert Fico, who has turned the country's foreign policy to more pro-Russian views and initiating reforms of criminal law and the media, which have raised concerns over weakening the rule of law.

Pellegrini, backed by the nationalist-left ruling coalition, had 56.7 per cent of the vote, versus 43.3 per cent for pro-Western opposition candidate Ivan Korcok, results from 80.1 per cent of voting districts showed.

Korcok could still win more votes in large, urban districts that report last, but prediction models by two Slovak media outlets showed he was unlikely to close the gap.

Slovak presidents do not have many executive powers, but can veto laws or challenge them in the constitutional court. They nominate constitutional court judges, who may become important in political strife over the fate of Fico's reforms, which would dramatically ease punishments for corruption.

Pellegrini, 48, has tried to portray Korcok as a warmonger for his support for arming Ukraine and suggested he may take Slovak troops into the war, which Korcok denies.

Pellegrini, seen as more moderate than Fico, said his election would not mean a rush to change foreign policy.

"This is not about the future direction of foreign policy, I am also a guarantee, like the other candidate, that we will continue to be a strong member of the EU and NATO," he said after voting in Rovinka on the outskirts of the capital.

The independent Korcok, 60, was Slovakia's envoy to the EU and later ambassador to the U.S., before taking the foreign affairs portfolio in center-right governments in 2021-2022.

At the time, Slovakia was a staunch ally of Ukraine, providing it with air defense and fighter jets. Fico's cabinet halted official supplies after taking power.

Pellegrini, now speaker of parliament, was a long-time ally of Fico, who picked him to be prime minister after Fico was forced to resign amid public protests against corruption following the murder of an investigative journalist in 2018.

He later split from Fico to set up his own party, Hlas (Voice), more centrist and liberal than Fico's populist-leftist SMER-SSD, but formed a government with Fico and the nationalist SNS last October.