The controversial leader of the Yisrael Beytenu party endorsed Likud's Benjamin Netanyahu Thursday, virtually ensuring that a right-wing coalition will govern the country.
Some see a risky 'one-state solution' as the only remaining option in the Israeli-Palestinian conflict.
Livni and Netanyahu are each vying to form a coalition. Soldiers' ballots did not change the outcome.
In a country divided between the centrist Kadima and hawkish Likud parties, a new kingmaker emerges from the far right.
With no official agreement, Israel's Kadima Party could falter in Tuesday's vote.
Benjamin Netanyahu, the Likud party hawk, leads in polls ahead of Tuesday's parliamentary election.