On Sunday, his chief of staff Graziano Delrio caused a stir by suggesting the government was considering raising taxes on government bonds, which are popular with Italian savers.
Renzi took office on Saturday promising a radical increase in tempo, with an overhaul of the electoral and constitutional system to ensure more stable governments in future, tax and labor reforms and a shake-up of the bloated public administration, all within his first 100 days.
The tone of his speech was direct and colloquial, in contrast to the sober style of his two predecessors, Letta and Mario Monti. Noting that, at 39, he was not even old enough to hold a seat in the Senate, where the minimum age is 40, he said that politics had lost touch with citizens.
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"If we'd paid the same attention to what people say in their local markets that we often paid to the financial markets, we would have noticed that the first thing people want is simplicity," he said.
He said the government's priority had to be to help small businesses and people who had lost their jobs and he promised to strengthen welfare protection for the unemployed.
The public administration would completely pay off its arrears of unpaid bills, completing a campaign to free up billions of euros owed to private sector suppliers begun by his predecessor Letta.
(Read more: Italy PM Letta quits: 'Demolition Man' Renzi steps up)
He gave little detail about how he intended to fill the funding gap left by paying off the arrears but said it could involve the state-owned investment holding Cassa dei Depositi e Prestiti (CDP).
A comprehensive package of reforms to the notoriously sluggish justice system would be completed by June and long-promised electoral and constitutional reforms would be in place and ready to go before parliament by the end of March.
Monday's Senate vote will be followed by a separate vote on Tuesday in the lower house, where the PD has a strong majority, and that will wrap up the parliamentary process required by every new government.