Andrej Babis, the second wealthiest Czech, leads the centrist ANO (Yes) movement which opinion polls show headed for victory in legislative elections later this year.
He is at the centre of a week-long political crisis sparked by doubts over his business dealings, which the tycoon insists are all legal.
Parliament wants him to explain how he raised the money to buy his sprawling Agrofert farming, chemicals and media conglomerate.
"When people like you (Babis) enter politics, it's a huge danger," Zaoralek said, during the special parliamentary sitting called to address Babis's alleged wrongdoing.
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Babis shot back calling the debate "a live execution" and "another mega-campaign against me."
A Slovak-born self-made magnate, Babis has become the EU state's most popular politician by selling himself and the party he forged 2012 as being tough on corruption, something voters perceive as pervasive in often murky Czech politics.
Babis is also under fire over leaked conversations revealing that he pressured a journalist from his media group to attack political rivals.
The 62-year-old Babis has refused to comment on the leaks.
Josef Mlejnek, a political analyst at Charles University in Prague, told AFP the recordings could dent his popularity.
"The recordings... Prove he's a liar," said Mlejnek, recalling that Babis vowed in 2013 to "never meddle in editorial matters."
Mlejnek said the current crisis was also partly triggered by the CSSD as an early campaign move ahead of the October 20 -21 elections.
"They (CSSD) didn't want to end up in opposition with ANO winning the election, so they decided to attack Babis hard, even at the cost of destroying the (coalition's) cabinet," he said.
The latest crisis in often turbulent Czech politics began on May 2 when CSSD head and Prime Minister Bohuslav Sobotka tendered his entire government's resignation in a bid to oust Babis.
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