KIEV — Campaigning began for a key presidential vote in Ukraine on Monday with President Petro Poroshenko facing an uphill re-election battle among voters disillusioned with corruption and the slow pace of reforms.

Poroshenko, whose government is locked in a conflict with Moscow-backed insurgents in the industrial east, trails two-time ex-Prime Minister Yulia Tymoshenko in the latest opinion polls.

Voting will take place on March 31, with a second round three weeks later if no candidate takes more than 50 percent.

Poroshenko, a 53-year-old chocolate tycoon, sailed to victory in a May 2014 election after a popular uprising ousted the Moscow-backed regime of Viktor Yanukovich.

He promised to pivot the ex-Soviet country of nearly 45 million people toward the West and has sought to push through ambitious reforms.

But critics say the economy is in tatters, corruption is rampant and Poroshenko has done little to rein in fellow oligarchs.

One poll this week showed 16.1 percent of expected voters planning to vote for Tymoshenko, ahead of Poroshenko with 13.8 percent.

After the 2014 uprising, Moscow annexed Crimea and supported Russian-speaking separatists in Ukraine’s east, in a conflict that has claimed the lives of more than 10,000 people.

The war has been a huge burden for the country’s struggling economy, with Poroshenko forced to rely on assistance from the West.

This month the International Monetary Fund confirmed it would give Kiev a $4 billion, 14-month loan.

Poroshenko is widely expected to stand for re-election even though he has not yet confirmed he is running.

His re-election chances looked even more bleak in November when a Ukrainian comic and showman, Volodymyr Zelensky, overtook him as the country’s second-most-popular likely presidential candidate.

But Poroshenko’s popularity ratings increased after he oversaw the creation of a Ukrainian Orthodox Church independent of Moscow.

His standing also received a boost after Russia seized three of Kiev’s navy vessels and two dozen sailors as they tried to pass from the Black Sea to the Sea of Azov in November.

Russian President Vladimir Putin accused Poroshenko of provoking the naval crisis in a bid to increase his popularity ahead of the vote.

“The elections will be very dirty and very complicated,” Anatoliy Oktysyuk, an analyst at Democracy House, a Kiev think tank, said. “The stakes are very high.”

He said many Ukrainians planned to vote for Tymoshenko “not because they support her but because they are against Poroshenko.”

Tymoshenko, 58, was a star leader of Ukraine’s 2003-04 Orange Revolution, served twice as prime minister and spent three years in jail for abuse of power.

She lost the 2010 election to Kremlin-backed Yanukovich and unsuccessfully ran against Poroshenko in 2014.

Pro-Russian lawmaker Yuriy Boyko and the head of the populist Radical Party, Oleg Lyashko, are among those also expected to run. — AFP