Yishai has yet to respond to the offer, and sought the advice of his Rabbi Meir Mazuz, a leading Sephardic haredi rabbi.
Yishai's activists sparked a storm in the political arena by publicizing ads for Yishai on social media urging voters to vote for Yachad "in order that there shouldn't be a child with two fathers."
Eli Yishai also argued that keeping Yahad as an independent party on a joint list with Shas would garner more votes than if he were simply to return to Shas.
Reconciliation efforts of the long-standing feud are afoot between Shas, Yahad, Chief Rabbi Yosef and Jerusalem Chief Rabbi Amar.
The two party leaders have been bitter enemies since Deri ousted Yishai as Shas chairman in 2013.
Former leader of Sephardic ultra-Orthodox party blasts cabinet decision to create egalitarian prayer space "an attack on the Holy of Holies."
"Deri is a wheeler-dealer, who must decide whether he represents the poor who he said were invisible poor or the gas tycoons," says former Shas chairman.
The prime minister meets with the former head of Shas amid reports of building right wing bloc ahead of next general elections.
Election leaves party with large debt, no party funding.
Eli Yishai may run in the J'lem mayoral election against Nir Barkat, given Uri Lupolianski announces that he’s not running.