An Orthodox Jew who lives in a West Bank settlement, Feiglin says religious nationalists can have more influence through Likud than by voting for their niche parties.
During the party primary, Feiglin denounced Likud establishment leaders like Mr. Sharon as tools of "secular leftist Ashkenazi elite" who ordered the destruction of Jewish settlements.
"When we vote right, what do we get? We get expulsions. We get disengagement," he told the party central committee before the election. "We get the left of the left."
In his many articles and within his movement, Feiglin has called for building a Jewish synagogue on Jerusalem's ancient Temple Mount – a move that would inflame tensions with the Muslim world. He says Israel's secular government should be more influenced by the Torah, though his campaign denies that he supports religious laws.
"The illusion of a center-right party was shattered this morning, and it's clear that this is the most right-wing extremist list the Likud has produced since its establishment," said Haim Ramon, a Kadima Knesset member, in an interview with Army Radio. "Any sane person will understand that you can't vote for the Likud."
Mr. Netanyahu and the rest of the Likud establishment are worried. Anti-Feiglin banners hung on the Jerusalem roadside read, "The left is praying for Feiglin."
"It might harm our chances to win the election because he and his group are very different from the Likud," said Yuval Steinitz, a Likud Knesset Member and Netanyahu loyalist before the primary. "Their positions are very much to the right of the Likud."