The premier, whose party backed Orsoni in his 2010 election, said the Venice mayor had a duty to resign ''once he made a plea agreement, declaring himself guilty."
Orsoni was among more than 30 people, including other politicians and officials, arrested last week in a wide-ranging probe that alleged the consortium building underwater barriers in the Venetian lagoon had amassed a $34 million slush fund abroad to bribe officials.
The mayor was accused of accepting contributions for his 2010 campaign from the slush fund, although he denies knowing that any of the donations to his campaign were illegal. He was released from house arrest Thursday after accepting a four-month suspended sentence.
The ambitious barrier project, meanwhile, has suffered long delays and is more than four times over its initial cost projection. It is currently expected to be finished by 2016.
Under the government's new measures, the country's anti-corruption czar will have the ability to take over parts of public works projects tainted by scandal, like the world's fair Expo 2015 in Milan swept up in a bribery investigation. Renzi said the move is critical to ensuring new investments are made in Italy, and that routing corruption is a long-term project.
''Let's be clear: corruption cannot be fought with new rules, corruption is fought with an educational and civic bet, and with a large investment in the country's moral conscience," Renzi said.
Also Friday, a longtime ally of former Prime Minister Silvio Berlusconi who authorities said fled to Lebanon to escape a prison sentence for Mafia association was extradited to Italy under Interpol guard. Marcello Dell'Utri was transferred to a prison in the northern city of Parma.
And another one-time Berlusconi aide, three-time government minister Claudio Scajola, was granted house arrest Friday weeks after being arrested on suspicion of aiding a businessman convicted of Mafia association to flee abroad.