Aide: Former Israeli PM Olmert will not run in election

The centrist Olmert had been mulling a political comeback since October, when Netanyahu called the election after his government failed to agree on the 2013 budget.

"He is not running," his aide, Yanki Galanti, told Reuters.

Olmert, 67, was forced to quit as prime minister in 2008 over corruption charges of which he was largely acquitted this year. He is internationally credited for pursuing peace with the Palestinians.

Right-wing Netanyahu, who polls predict will win the ballot, has come under international pressure in the past week after his government announced plans to expand Israeli settlements in the occupied West Bank.

Israeli commentators were divided on whether an Olmert candidacy would have helped to unite an already splintered center-left opposition, or would have further fractured the bloc.

Israelis go to the polls on Jan. 22.