KIEV, Ukraine (AP) " The candidate who placed third in the first round of Ukraine's presidential election conceded defeat Tuesday but alleged the incumbent who came in second rigged the results in his favor.

Opinion polls had shown Yulia Tymoshenko, a former prime minister who has been a fixture in Ukrainian politics for two decades, leading the race until a few months before Sunday's election.

With nearly 99% percent of ballots counted, comic actor Volodymyr Zelenskiy had garnered 30% of the vote. President Petro Poroshenko was next with just under 16%, while Tymoshenko received 13%.

That means that Ukraine's new president will be elected in a runoff between Zelenskiy and Poroshenko on April 21.

In her concession remarks, Tymoshenko alleged Poroshenko had manipulated the vote.

"He should not be in the runoff," she said. "He got there by cheating."

Tymoshenko did not specify what kind of election interference she thought occurred, although she had accused Poroshenko in the days before the election of buying votes.

The president responded last week by promising a democratic election, saying Ukraine had a lot at stake in monitors' views of the process.

Tymoshenko said she would not contest the election results because she thinks Poroshenko controls the courts. She refused to either Zelenskiy or Poroshenko for the runoff.

She said she and her party would now focus on the parliamentary election in the fall, which could give her a post in a new government.

"The chance we've lost in the first round of the presidential election is just one chance," Tymoshenko said. "We still have one opportunity left to bring in a dramatic change, to implement a new course, and this is the next parliamentary elections."

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Nataliya Vasilyeva in Moscow contributed to this report.