Ukraine's pro-Western President Petro Poroshenko launched his bid for a second five-year term in front of thousands of supporters on Tuesday, ahead of a tight election race in March.

A 53-year-old confectionary magnate and one of Ukraine's richest men, Poroshenko has steered the country on a pro-Western and pro-NATO course since coming to power in the aftermath of the 2014 Maidan protests and Russia's annexation of Crimea.

"The feeling of deep responsibility before the country, before contemporaries, before past and future generations prompted me to decide to run again for the presidency," Poroshenko said.

Polls show Poroshenko trailing the opponent he defeated five years ago, opposition leader Yulia Tymoshenko, a veteran former prime minister who has pledged to clamp down on graft, raise wages and lower household energy prices

Among his policy priorities, Poroshenko said Ukraine would apply to join the European Union by 2024, and a special court to try corruption cases would be up and running this year.

Poroshenko's popularity has dwindled over patchy efforts to tackle corruption and his failure to end the conflict in the eastern Donbass region that has killed more than 10,000 people.

He has also failed to raise living standards in one of Europe's poorest countries.

Promises to defend against Russian interests

While apologizing for mistakes, Poroshenko cast himself as the man to guard Ukraine against Russia and populism, and keep the country on its Western course. Patriotic songs and videos, showing footage of soldiers at the front or the president meeting world leaders, preceded his speech.

"None of my steps, successful or not, contradicted the strategy of a complete break with the colonial past, of Ukraine going its own way, of a civilization alliance with Europe," he said. "And we have no right to stop halfway."

Tymoshenko, a fiery speaker who was jailed under Kremlin-backed leader Yanukovich, launched her campaign last week. Volodymyr Zelenskiy, a political novice who achieved fame as a comic actor, is also seen as a strong challenger.

Poroshenko is likely to promote himself as a less radical choice than Tymoshenko, whose plans for more state spending could set her on a collision course with the International Monetary Fund and other foreign lenders who have pumped in billions to keep Ukraine's war-scarred economy afloat.

Yulia Tymoshenko, the former prime minister who was once jailed under a previous regime, is expected to be Poroshenko's main opposition in the presidential campaign. (Valentyn Ogirenko/Reuters)

Poroshenko can boast some successes. He secured visa-free travel to the European Union for Ukrainians. He also led efforts to create a national, independent Orthodox church that threw off centuries of ties to the Russian clergy.

While he has not won the war in the east, as he had promised to do within weeks, he has not lost it either. The 2015 ceasefire has largely held despite regular deadly clashes.

He also successfully lobbied for U.S. President Donald Trump's administration to supply lethal defensive weapons to Ukraine and for the EU and Washington to keep sanctions on Russia.

But corruption still festers, top officials suspected of bribe-taking have stayed out of jail, anti-corruption activists have been attacked, and reforms sometimes stalled or reversed.

Ukrainian President Petro Poroshenko wants Canada to restart a program to supply the Ukrainian military with satellite images to monitor Russian and separatist rebel troop movements 8:50

Poroshenko's re-election bid coincided with the release of watchdog Transparency International's latest Corruption Perception Index. Ukraine has climbed 10 places since last year but still languishes in 120th place out of 180.

The election will be fought against a backdrop of plunging relations between Ukraine and Moscow since Russia's annexation of Crimea in 2014.

Kyiv has accused Russia of orchestrating large-scale cyberattacks as part of a "hybrid war" against Ukraine, which Moscow repeatedly denies. The head of Ukraine's cyber police told Reuters last week that officials have noticed an increase in cyberattacks on electoral servers and personal computers of election staff heading into the campaign.

The vote is to be held on March 31, with parliamentary elections in October.