Oleksandr Danyliuk, former Ukrainian Minister of Finance and advisor to presidential candidate Volodymyr Zelenskiy, talks during an interview with The Associated Press in Kiev, Ukraine, Wednesday, April 3, 2019. The thriving campaign of comedian Volodymyr Zelenskiy to be Ukraine’s president may seem improbable, but his campaign adviser says the country has reached the point where it needs reforms from seemingly unlikely sources. Oleksandr Danylyuk spoke to The Associated Press on Wednesday, three days after the election first round in which Zelenskiy easily outpaced incumbent Petro Poroshenko. (AP Photo Efrem Lukatsky)

MOSCOW (AP) — 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.

Oleksandr Danyliuk, former Ukrainian Minister of Finance and advisor to presidential candidate Volodymyr Zelenskiy, talks during an interview with The Associated Press in Kiev, Ukraine, Wednesday, April 3, 2019. The thriving campaign of comedian Volodymyr Zelenskiy to be Ukraine’s president may seem improbable, but his campaign adviser says the country has reached the point where it needs reforms from seemingly unlikely sources. Oleksandr Danylyuk spoke to The Associated Press on Wednesday, three days after the election first round in which Zelenskiy easily outpaced incumbent Petro Poroshenko. (AP Photo Efrem Lukatsky)
Oleksandr Danyliuk, former Ukrainian Minister of Finance and advisor to presidential candidate Volodymyr Zelenskiy, talks during an interview with The Associated Press in Kiev, Ukraine, Wednesday, April 3, 2019. The thriving campaign of comedian Volodymyr Zelenskiy to be Ukraine’s president may seem improbable, but his campaign adviser says the country has reached the point where it needs reforms from seemingly unlikely sources. Oleksandr Danylyuk spoke to The Associated Press on Wednesday, three days after the election first round in which Zelenskiy easily outpaced incumbent Petro Poroshenko. (AP Photo Efrem Lukatsky)
Oleksandr Danyliuk, former Ukrainian Minister of Finance and advisor to presidential candidate Volodymyr Zelenskiy, talks during an interview with The Associated Press in Kiev, Ukraine, Wednesday, April 3, 2019. The thriving campaign of comedian Volodymyr Zelenskiy to be Ukraine’s president may seem improbable, but his campaign adviser says the country has reached the point where it needs reforms from seemingly unlikely sources. Oleksandr Danylyuk spoke to The Associated Press on Wednesday, three days after the election first round in which Zelenskiy easily outpaced incumbent Petro Poroshenko. (AP Photo Efrem Lukatsky)
Oleksandr Danyliuk, former Ukrainian Minister of Finance and advisor to presidential candidate Volodymyr Zelenskiy, talks during an interview with The Associated Press in Kiev, Ukraine, Wednesday, April 3, 2019. The thriving campaign of comedian Volodymyr Zelenskiy to be Ukraine’s president may seem improbable, but his campaign adviser says the country has reached the point where it needs reforms from seemingly unlikely sources. Oleksandr Danylyuk spoke to The Associated Press on Wednesday, three days after the election first round in which Zelenskiy easily outpaced incumbent Petro Poroshenko. (AP Photo Efrem Lukatsky)
Oleksandr Danyliuk, former Ukrainian Minister of Finance and advisor to presidential candidate Volodymyr Zelenskiy, talks during an interview with The Associated Press in Kiev, Ukraine, Wednesday, April 3, 2019. The thriving campaign of comedian Volodymyr Zelenskiy to be Ukraine’s president may seem improbable, but his campaign adviser says the country has reached the point where it needs reforms from seemingly unlikely sources. Oleksandr Danylyuk spoke to The Associated Press on Wednesday, three days after the election first round in which Zelenskiy easily outpaced incumbent Petro Poroshenko. (AP Photo Efrem Lukatsky)
Former Ukrainian Prime Minister Yulia Tymoshenko speaks during her press conference in Kiev, Ukraine, Monday, April 2, 2019.  Timoshenko has accused incumbent Ukrainian President Petro Poroshenko of vote rigging in the first round of the March 31 presidential election, but she is not planning to challenge the results.(AP Photo/Efrem Lukatsky)
Former Ukrainian Prime Minister Yulia Tymoshenko speaks during her press conference in Kiev, Ukraine, Monday, April 2, 2019.  Timoshenko has accused incumbent Ukrainian President Petro Poroshenko of vote rigging in the first round of the March 31 presidential election, but she is not planning to challenge the results as she believes the courts are also controlled by the president. (AP Photo/Efrem Lukatsky)