Rome: Italian Prime Minister Matteo Renzi’s centre-left Democratic Party (PD) has reached an accord with centre-right parties over proposals to curtail the powers of the Senate, one of the key planks in a wider constitutional reform package.

The changes, agreed by party officials late on Friday, are intended to create the conditions for more stable government.

They would concentrate power in the lower house and make it easier for a party to win a reliable parliamentary majority.

Under the current system of “perfect bicameralism,” the Senate has virtually equal powers with the lower house but is elected through regional votes rather than a single national ballot. That increases the chances the two houses will end up with different majorities.

Under the accord, the Senate would become a regional chamber which would lose its power to pass legislation and to vote “no confidence” and bring down a government. It would still have the power to request amendments and vote on constitutional issues.

Responding to pressure for a cut in the cost of the overall political system, the number of senators would be cut from 315 to 100. Instead of being directly elected, they would mainly be mayors and local government representatives with a small number nominated by the president.

The accord will require a two-thirds majority in parliament to change the constitution, which it should get if the agreement with the opposition holds up. It is expected to be brought up for debate in parliament next month.

The agreement follows months of wrangling between the PD and former Prime Minister Silvio Berlusconi’s Forza Italia party. A deadlock after last February’s election had forced centre-left and centre-right parties into an unwieldy and fragile coalition, strengthening long-standing calls for an overhaul of the system.

A separate reform of the voting system is currently being discussed by the parties, with representatives from the PD expected to meet members of the anti-establishment 5-Star Movement next week.