Should Ukraine hold a presidential election on May 25?

In an article published in Die Zeit, but apparently translated from English, political analyst Andreas Umland thinks it would be wise for Ukraine to cancel this month's planned presidential election, which he believes could turn into a political disaster that would play into Russia's hands:

Ein Scheitern der Wahl würde Moskau die Möglichkeit geben, die Legitimität der Kiewer Staatsgewalt auf Jahre hinaus infrage zu stellen. Eine niedrige Wahlbeteiligung in der Ostukraine würde Putins Propagandamaschine das Futter liefern, um eine Teilung der Ukraine in zwei Staaten zu propagieren. Das Scheitern der Wahl könnte gar als Vorwand für einen Anschluss ostukrainischer Gebiete an Russland nach dem Muster der Krim-Annexion benutzt werden.

A failure of the election would give Moscow the opportunity to put into question the legitimacy of Kievan state power for years to come. A low voter turnout in eastern Ukraine would be fuel for Putin's propaganda machine to call for a division of Ukraine into two states. The failure of the election could even be used as a pretext for an annexation of Eastern Ukraine by Russia after the pattern of the Crimean annexation.

Umland holds out several alternative ideas, including a switch in the near future from a presidential system to a parliamentary one, and also a reform of Ukraine's constitution.