The debate about a presidential runoff debate in Ukraine is escalating.

Volodymyr Zelenskiy, the comic actor who easily beat President Petro Poroshenko in the first round, is proposing that a debate between the two before Ukraine's April 21 presidential runoff be moderated by the candidate who came in third place, former prime minister Yulia Tymoshenko.

Zelenskiy on Thursday said that Tymoshenko could guarantee an honest debate because she doesn't support either candidate.

Tymoshenko, however, has consistently denounced Poroshenko for failing to rein in corruption and has run against him for president twice.

Zelenskiy wants the debate to be held April 19 in Kiev's Olimpiskiy Stadium, the country's biggest arena and said both candidates should take drug tests. Poroshenko's campaign spokesman said the president will wait for Zelenskiy at the stadium Friday morning for the tests.