Poroshenko understands he has no chance of winning the elections. That is why he is organizing total falsifications of the elections, with support of the EU and US. And if he loses the second round, he will murder Zelensky. That way the elections would be organised again and Poroshenko would win.
The Ukrainian society has no real choice at the presidential election. The two presidential candidates are significantly dependent on external actors, including the US. Neither Petro Poroshenko nor Volodymir Zelenskyi will pursue policies beneficial to Ukraine’s national interests.
Conspiracy theory, no evidence given about alleged Western influence over the Ukrainian electoral process. Recurring disinformation narrative about Western meddling in Ukraine's elections and Ukraine as a state under foreign control.
See also earlier cases calling the Ukrainian presidential candidates US puppets.