Former Israeli kingmaker poised for comeback

A Deri-led party, however, would have additional influence. While no official polls have been conducted, Shas' internal estimates are that Deri could draw more votes away from Likud, which is also popular with Mizrahi Jews.

Nitzan Chen, a former journalist who authored a book about Yosef, said the rabbi is interested mostly in whichever candidate can win the most seats — and therefore deliver funding to the party's religious institutions.

That would appear to be Deri, whose political appeal transcends the ultra-Orthodox world and who dreams of turning the party into a national force with broad appeal.

"Deri sees himself as a chairman who is not just an ultra-Orthodox leader, but a national leader," said Chen. "He offers Shas a wider worldview. He looks to represent not only the traditional voters but the proletarian as a whole."

Deri, unlike Yishai, also wouldn't automatically align himself with the prime minister on diplomatic issues.

Polls show Netanyahu and his right-wing bloc to be far ahead of all competitors. Deri is unlikely to change the overall balance of power, but he could make things interesting.

"The bloc is solid, but Deri could soften things within his party and within the coalition," said political commentator Hanan Crystal. "Deri is more seasoned and more pragmatic. He can hurt Netanyahu, he can moderate him, but he can't prevent him from becoming prime minister again."