An official from Israel's main opposition faction says former Foreign Minister Tzipi Livni has agreed to give up a power-sharing agreement with the group's leader if they win Tuesday's parliamentary election.

Livni formed the Zionist Union with Isaac Herzog to bolster the opposition's chances against Prime Minister Benjamin Netanyahu's Likud Party.

But with the union leading in opinion polls, lawmaker Shelly Yacimovich told Channel 2 TV that Livni no longer wants to rotate the prime minister's job.

Livni, a former top negotiator with the Palestinians, has been noticeably absent from the campaign.

Channel 2 analysts said the move was meant to strengthen the opposition a day before the election.