Italy's new prime minister threatened on Monday to resign if a plan to reduce the powers of the upper house of parliament, a central part of his ambitious constitutional reform agenda, is blocked, Reuters reported. In the latest step of Matteo Renzi's reform drive, the cabinet is due to approve a draft bill on Monday to transform the Senate into a non-elected chamber stripped of the power to approve budgets or hold votes of no-confidence in a government. Renzi, who became Italy's third prime minister in a year in February, has said that without a change in the system, the country risks being stuck with a rotating series of short-lived governments incapable of passing meaningful economic reforms. "I have put all my credibility into this reform; if it doesn't succeed, I can only assume the consequences," Renzi, Italy's youngest prime minister at 39, told the Corriere della Sera newspaper. Renzi, head of the centre-left Democratic Party, made a similar threat to quit over Senate reform on March 12 while pushing through a package of tax cuts aimed at reviving Italy's sluggish economy, the third largest in the euro zone.