By Antonella Cinelli and Steve Scherer
ROME (Reuters) - Italian Prime Minister Matteo Renzi on Tuesday moved one step closer to passing a constitutional reform aimed at streamlining the lawmaking process, as divisions within opposition leader Silvio Berlusconi's party widened.
The lower house of parliament voted 357 to 125, with seven abstentions, to pass a constitutional change that will reduce the size and powers of the Senate.
Under the lengthy procedures required for constitutional changes, both houses of parliament now must pass the reform again at least once. It will probably then face a national referendum and so is unlikely to become law before next year at the earliest.
If passed, the law would return to Rome some powers now held by the regional governments, and the support of the upper house, the Senate, would no longer be needed to form a government or pass most laws.
Renzi has said the measure is central to his push to modernise Italy. He lauded the vote in a Tweet, saying it would make the "country more simple and just".
Though Renzi ran into some trouble with left-wing members of his own Democratic Party (PD), eight of whom voted against the bill, it easily passed even without votes from Berlusconi's Forza Italia party, which had supported the reform during a previous vote in the Senate.
But Renzi has a narrower majority in the Senate, and so may need Berlusconi's support if he is to ultimately pass this reform, together with a planned change to the electoral law, in coming months.
The 78-year-old Berlusconi last year sealed a pact with Renzi to change the constitution and draft a new electoral law.
But the media magnate and four-time premier declared the pact dead last month after Renzi backed constitutional judge Sergio Mattarella to become the country's new president, refusing to concede to Berlusconi's demands for another candidate.
Berlusconi ordered his party members to vote against the reform on Tuesday and though only one of his lawmakers disobeyed him, 18 others said they held the party line only out of their personal "affection" for Berlusconi.
In a letter, the lawmakers said the party was "not united nor in agreement" in abandoning the reform, which Berlusconi himself has repeatedly said is needed. They called for the party to adopt a more democratic internal decision-making process.