ROME (Reuters) - Italian Prime Minister Matteo Renzi said on Thursday he would not take any part in efforts to form a temporary or technocratic government if he loses next month's referendum on constitutional reform.

Renzi has promised to resign if he loses the vote, and with the majority of polls pointing to that outcome, attention has focused on what may happen after the Dec. 4 ballot.

Many observers expect a temporary government to be formed, charged with drafting a new electoral system, or a so-called "technical" government of experts without party affiliation.

Renzi said the electoral law would have to be changed whatever the outcome of the referendum, but indicated he would not be the person to re-write the legislation if his flagship constitutional reform is rejected.

"I can't be someone who negotiates a deal with the other parties to create a little government or one with a limited goal (to change the electoral system)," he told radio station RTL.

"I'm not willing to take part in old-style political games. Either we change or I have no role to play," he said.

The constitutional reform proposes drastically curbing the role of the upper house Senate, a move that Renzi says will simplify decision-making and ensure stable government. Opponents say it will make the legislative process more complicated and reduce democratic checks and balances.

The current electoral law, which Renzi pushed through parliament in 2015, introduces a two-round voting system and offers the winner a handsome majority in the lower house.

However, the law does not cover the Senate and Italy risks political paralysis if it went to elections with different systems governing the vote in the two chambers.

Mainstream parties on both the left and right worry that the reform could help the anti-system 5-Star Movement, which all recent polls have said would win power under a two-round voting system.

A new poll on the referendum by the CISE agency published in Il Sole 24 Ore newspaper on Thursday put 'No' ahead by 34 percent to 29 percent with 37 percent undecided or planning to abstain.

(Reporting by Antonella Cinelli, writing by Gavin Jones and Isla Binnie; Editing by Crispian Balmer)