A snap parliamentary election will be held within two months of new Ukrainian President Volodymyr Zelenskiy signing a formal dissolution decree.
Volodymyr Zelensky is the Ukraine's youngest post-Soviet president. As he starts a five-year term, early elections are a chance for Zelenskiy to strengthen his position and sideline allies of Poroshenko.
As his first act, he dismissed the parliament still dominated by loyalists of his defeated predecessor, setting up an election in two months in which his new party has a chance to win its first seats.
On Monday, Vladimir Zelensky took the oath of office as President of Ukraine at the Ukrainian parliament meeting.
Zelenskiy replied: "They understand the Ukrainian language, yes".
Mr Zelensky - whose only previous political experience was appearing as president in a popular TV show - announced he would dissolve parliament in order to call an early election, originally scheduled for October.
Zelenskiy's attempt to dissolve the parliament already faces a challenge.
Parliamentary rules prohibit it from being disbanded for 30 days after a coalition breaks up, a delay that would create another delay since it would mean the parliament would already be in the final six months of its a term, when it can not be dissolved. "Do it and you will deserve medals", Zelenskiy said.
"The legally dubious decision to disband parliament will certainly be contested in court but Zelensky has shown that it is going to be him who will lay down the agenda and that he will dominate the political landscape".
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Zelenskiy played the part of Ukrainian president in his TV comedy show before life imitated art and the Ukrainian people voted him in by a landslide in April, winning 73.5 percent of the vote compared to 26.5 percent for incumbent Petro Poroshenko.
Even before he disbanded the Supreme Rada, which had been one of his campaign promises, the 41-year-old Zelenskiy had upended the traditions of Ukrainian politics.
He ditched the idea of a traditional motorcade to his inauguration, walking to parliament in the capital of Kiev through a park packed with people. Mr. Zelenskiy told lawmakers they only have a few weeks to support his motions, as that's as long as the current Parliament has.
Defence Minister Stepan Poltorak and the head of the SBU security service Vasyl Grytsak tendered their resignations on Monday. That move would be largely symbolic because it would have to be approved by the Parliament.
Supporters hold Ukrainian flags during former Ukrainian prime minister and now presidential candidate Yulia Tymoshenko's pre-election rally in Kiev, on March 29, 2019, ahead of the presidential election on March 31.
He also vowed that his first task was to bring a ceasefire in the conflict with Moscow-backed separatists in eastern Ukraine that has so far caused some 13,000 deaths.
"I am not ashamed of what we were able to do", he said. Four hundred fifty snouts who eat greedily but are never full, while we cannot buy proper food for ourselves, cannot get proper clothing, cannot afford proper housing. "But we need to be the one to finish it".
In his speech, Mr. Zelensky referred to his background as a comedian. 'In my life, I've tried to do all I could to make Ukrainians smile, ' he said.