Shas has been in Labor coalitions as well as Likud coalitions. Likud, Jewish Home and United Torah total only 49 seats. Yeah Atid, Labor , Hatnuah and Metetz together have 50 seats. Shas would put the Center-Left over the top.
Judge orders Jerusalem Gay Pride attacker to undergo psychiatric evaluation (Haaretz)
from the article: Israel election exit polls reveal tight race between left and right