Hungarian Prime Minister Viktor Orban's nationalist Fidesz party won the most votes in Sunday's European Parliament elections, but preliminary results showed its worst performance in years.

Orban's Fidesz party had 43% of the vote, down sharply from 52% support in the 2019 EU elections.

Opposition newcomer Peter Magyar's center-right party called Respect and Freedom (TISZA) stood at 31% of the vote, with 55% of the vote counted.

"Although we don't know the results yet," he said, "today is a milestone. I would like to ask everyone to remember this day well. On June 9, 2024, an era has come to an end."

Magyar plans to use the elections to propel himself and his movement to challenge Orban in the next national ballot, scheduled for 2026.

Orban, however, said the results affirmed his government's policy course.

"In a war situation and in a difficult battle, we have scored important victories," Orban told supporters.