With an early election likely in February or March, the surveys on Tuesday gave Sharon 30-33 seats in the 120-member parliament, enough to make his still-unnamed party the biggest faction in a governing coalition and virtually ensure him a third term.
Lawmakers began discussions on a resolution that will set an election date against the backdrop of the surveys, indicating the biggest gamble of Sharon's long political career could pay off.
In a move that could reshape Israeli politics for years to come, Sharon left the party he co-founded three decades ago, saying he could not push for peace with the Palestinians while "wasting time" battling far-right rivals in Likud.
Likud came out a distant third in the polls in the Yedioth Ahronoth, Haaretz and Maariv newspapers, with 12 to 15 parliamentary seats.
Centre-left Labour, led by its fiery new leader, Amir Peretz, was projected to win 25 or 26 seats.
But commentary accompanying the Haaretz poll cautioned that initial enthusiasm over Sharon's breakaway move could cool.
New parties have historically not fared well in Israel, and Sharon faces stiff opposition from the frontrunner to succeed him as Likud leader, hardliner Benjamin Netanyahu. Likud's Central Committee was to meet on Thursday to set a primary date.
The poll showed Peretz's Labour
as likely to gain 25 or 26 seats
Despite Sharon's oft-repeated pledge to make "painful concessions" for peace, they note he has vowed to hold on to major settlement blocs in the occupied West Bank in a final peace deal, a move the Palestinians fear will deny them a viable state.
Sharon's party has been joined by a dozen Likud veterans, and confidants said he may recruit colleagues from among ex-security chiefs, moderate religious Zionists and academia.
But hawkish Defence Minister Shaul Mofaz said he would remain in the Likud and run for party leader.
Many in the Likud saw the Gaza pullout as a surrender to violence.
Foreign peace mediators hailed it as an opportunity to kick-start talks with the Palestinians.