Nazanine Moshiri, Al Jazeera's correspondent in Warsaw, said: "The race here is still very much wide open."
Speaking to Al Jazeera, Dariusz Rosiak, a Polish journalist, said: "He [Kaczynski] will try to get as much support as he can from ... the left wing voters who voted over 13 per cent for their candidate.
"It will be a clash for these two candidates [Kaczynski and Komorowski], for the votes of this part of the electorate.
Kaczynski is a conservative politician ... but to a large extent the main theme of his politics is solidarity, he will appeal to the social conscience of the voters, he will say 'I will protect the less well off people in this country'."
Kaczynski, a combative nationalist, is vying to replace his twin brother Lech Kaczynski, whose death in a plane crash in Russia in April forced the early election.
Komorowski, the speaker of parliament and the country's acting president, shares Tusk's vision of a Poland firmly anchored in the European mainstream.
He favours working closely with Germany and other EU partners and trying to improve long troubled ties with Russia,
Kaczynski is opposed to joining the euro any time soon and is distrustful of the EU, Russia and Germany.
While the prime minister holds most of the power in Poland, the president can veto laws, appoint key officials and also has a say in foreign and security policy.