MOSCOW — Ukrainians voted on Sunday in an early parliamentary election called by President Volodymyr Zelensky, a former comedian who was elected in April, as he seeks to strengthen his position in a country that has been at war with Russian-backed rebels for more than five years.
Mr. Zelensky, 41, has positioned himself as an outsider to Ukraine’s ruling class, which many voters consider hopelessly corrupt. During his presidential campaign, he promised an improvement in living standards and vowed to deliver a peaceful settlement of the conflict with separatists in eastern Ukraine.
Once in office, however, he discovered that his powers were hemmed in by lawmakers from the existing political elites. When he tried to dismiss the foreign minister and the prosecutor general, for instance, Parliament refused to endorse the moves.
Speaking at a news conference in June, Mr. Zelensky said that the snap parliamentary election should “speed up the reboot of the Ukrainian political system that has been mired in corruption.”
According to most recent polls, Mr. Zelensky’s party, called Servant of the People, is polling at around 50 percent, putting it in a good position to win enough seats to form a government.
If the party — named after the television comedy in which Mr. Zelensky played a teacher who unexpectedly becomes president — fails to win a majority, then it would probably look to form a coalition government. The most likely partners appear to be either a pro-European, center-right party led by Sviatoslav Vakarchuk, a rock star, or the populist party of former Prime Minister Yulia V. Tymoshenko.
The main parties running in opposition to Mr. Zelensky are the pro-Russian Opposition Bloc, which is currently polling in second with about 10.5 percent, and European Solidarity, the party of Mr. Zelensky’s predecessor, Petro O. Poroshenko. The Opposition Bloc is led by Viktor Medvedchuk, an ally of President Vladimir V. Putin of Russia. European Solidarity is polling around 7.7 percent.
Vladimir V. Fesenko, a political scientist who heads Penta, a research organization in Kiev, the Ukrainian capital, said there was “a high probability” that Mr. Zelensky’s party would take control of Parliament.
“This will be in contrast to the current situation when the Parliament blocks almost all of his initiatives,” Mr. Fesenko said.
Olga Labinina, speaking outside a polling station in Kiev on Sunday, said that she had voted for Mr. Zelensky’s party because she hoped to see change in the country. The previous government “has betrayed our trust,” Ms. Labinina, 50, said.
The Ukrainian Parliament has 450 seats, with 225 elected from party lists according to the overall vote share and the rest chosen by district. After the annexation of Crimea by Russia in 2014 and because of the continuing conflict in eastern Ukraine, 26 election districts do not elect their representatives.
While Mr. Zelensky has cast himself as an alternative to the self-interested political factions that came before him, he has faced increased scrutiny about his connections to one of Ukraine’s most powerful oligarchs, Ihor Kolomoisky. Mr. Kolomoisky owns the television network that has been buying content from Mr. Zelensky’s production company. Mr. Zelensky has denied that his business connections with Mr. Kolomoisky go any further than that.
Nonetheless, the links have raised fears that a familiar story could be repeating. Since Ukraine’s independence in 1991, oligarchs have exercised a vast influence over the country’s politics.
Vadim Y. Karasyov, a political scientist who heads the Institute of Global Strategies in Kiev, said that, with new members in Parliament, policy would likely be more centrist and less nationalist. But the oligarchs who have exerted disproportionate power over Ukraine, he said, will remain influential even after the parliamentary elections.
“There will be many new faces, but in terms of who rules over the country informally, things will remain the same,” he said. “The overall course will be more centrist, the government will balance between Russia and the West, and will attempt to direct its attention to internal affairs.”
Mr. Fesenko, the Penta analyst, said that there would be one probable difference, however: Mr. Zelensky would be on the hook for any mistakes.
“The argument that he cannot implement his policies will no longer work, he will have the decisive influence over the central government and full responsibility for everything that is happening in the country,” Mr. Fesenko said.