Amir Peretz on Thursday became the second former Labor Party leader in the space of a week to abandon his political home in favor of Tzipi Livni’s new Hatnua (The Movement), with a dramatic announcement that came close on the heels of a similar move by Amram Mitzna.

Peretz shocked followers of Israeli politics when he took to the stage alongside Tzipi Livni during a press conference in Tel Aviv, announcing after a lengthy exposition about his political career that he had chosed to join her party rather than play second fiddle to his former protégé, Labor chairwoman Shelly Yachimovich.

A former Histadrut Labor Federation chairman, Peretz was Yachimovich’s political patron when she joined Labor in 2005. But when Yachimovich beat him in the race for the party’s chairmanship in September 2011, the two had a falling out.

Peretz is considered the father of Israel’s highly successful Iron Dome missile defense system, having pushed to fund the system during his term as defense minister in 2006-7.

At Thursday’s press conference, Peretz said he had chosen to leave Labor because, under Yachimovich, the party had abandoned its left-wing values of pushing for peace with the Palestinians. He said that all his attempts to reach out to the Labor chair had been stonewalled.

“Yachimovich sees the vision of peace as an electoral liability; I see it as an asset,” said Peretz, who was elected to the second spot in Labor’s Knesset slate in party primaries held just last week.

“I don’t plan to waste time and energy in battles between left and center,” he continued. “I don’t plan to fight with Labor; I wish the best of luck to the party and my friends there.”

Peretz proceeded to reach out to voters on the right, particularly Likud faithful from underprivileged backgrounds.

“I love Likud voters; they are warm, patriotic and caring people who believe that the Likud-Beytenu will only lead them toward extremism and global isolation,” said Peretz. “I turn to all the Likudniks in the periphery: You will bring hope to the state of Israel. Prove to Netanyahu and Liberman that you are not in their pockets, that he can’t ignore you for four years. Vote for Tzipi Livni’s new movement.”

Likud and Avigdor Liberman’s Yisrael Beytenu last month signed an election alliance, presenting a joint list of candidates.

Peretz became Labor chairman in 2006, beating Shimon Peres in the party primaries, before giving up the top spot to Ehud Barak a year later in the wake of the failed Second Lebanon War, which took place under his watch as defense minister.

Welcoming Peretz to the party, Livni on Thursday said that Yachimovich had refused her offer of a power-sharing deal, including alternating the prime-ministership, as part of an agreement to field a joint Knesst slate to counter the combined Likud-Yisrael Beytenu.

“Luckily I am not the only one who believes in joining forces to counter the challenges that lie ahead,” Livni quipped in reference to her spurned offer.

The Labor Party issued a caustic response to Peretz’s announcement.

“With great relief we bid farewell to a person who tried, and failed, to sabotage the party at the height of its strength and popularity,” a statement from the party read. “His union with Tzipi Livni will not harm Labor in the slightest.”

Labor’s Isaac Herzog expressed surprise at the move, calling it “the height of political opportunism.”

Feminist activist and former columnist Merav Michaeli, who placed fifth in Labor primaries and is considered a confidante of Peretz, said the decision was not unexpected, but that she would not be joining him in Hatnua.

Yair Lapid’s Yesh Atid party issued a statement calling Peretz’s move the “most odious trick of all time.” The scathing comment employed the Hebrew term targil masriah, which was coined by Yitzhak Rabin in 1990 in response to Shimon Peres’s failed attempt to establish a narrow coalition — foiling a Yitzhak Shamir-led national union government — by concocting a clandestine deal with the ultra-Orthodox Shas party.

“Livni and her people have nothing in common other than the need to cling to their seats in power,” the statement added.

“The public sees what’s going on in the political arena and is disgusted by the ego, opportunism and flip-flopping” apparent in Peretz’s decision, said Meretz chairwoman Zahava Gal-on. “I am glad that Meretz is a safe harbor of integrity and is committed to ideology and not seats.”

A statement from Likud read: “On the opposing side of a united right wing that maintains its values to ensure the vital security interest of Israel and its citizens, we see a divided left that is willing to risk those interests for a Knesset seat.”

Earlier Thursday, Hatnua received another boost to its security credentials with the announcement that Maj. Gen. (res.) Elazar Stern was officially joining the party after weeks of speculations to that effect. Stern, a former member of the General Staff, is likely to be placed fourth on the party’s list.

Stern, 56, served as the IDF’s chief education officer and chief Human Resources officer, before retiring in 2008. Since then he has volunteered as CEO of The Foundation for the Benefit of the Holocaust Victims in Israel.

“I have no doubt that Elazar is an example for those who want to step up and make a difference. Elazar shares in the belief that in order for Israel to remain a Jewish state, it must adopt the two-state solution and engage in active negotiations in order to achieve it,” Livni said in a statement to the press.

The statement made it clear that Stern would be granted voting freedom on matters relating to diplomatic affairs, suggesting that the two had chosen to work together despite not seeing eye-to-eye on some issues. Stern reportedly holds views further to the right than Livni.

Stern told the Walla news website that he had decided to join the new party because he believed it was the “best and most trustworthy platform through which to promote matters important to me.”