Prime Minister Benjamin Netanyahu and Foreign Minister Avigdor Liberman on Thursday night made official the news of a merger between their respective Knesset factions, Likud and Yisrael Beytenu, saying the new right-wing super-faction would improve governability in Israel and allow them to tackle burgeoning internal and external challenges facing the country.

“A joining of forces will give us the strength to defend Israel from military threats, and the strength to spearhead social and economic changes in the country,” Netanyahu said, standing alongside Liberman in an address to the media at Jerusalem’s Dan Panorama Hotel. “We face challenges, and this is the time to join forces for the sake of Israel’s future. Which is why Likud and Yisrael Beytenu will run together, on a single ballot” in the general elections on January 22.

“We will ask the public for the mandate to lead the State of Israel with strength in the coming years. This will greatly strengthen the government, the prime minister, and the country,” Netanyahu added. “A clear mandate will allow me to focus on what’s really important.”

Netanyahu cited the Iranian threat and Israel’s rising cost of living among the challenges that would have to be faced by his government in an unequivocal, determined manner.

Speaking after the prime minister, Liberman said: “The joining of our forces presents a combination, as you said, of strength and unity. This is what the residents of Israel are expecting today…. We spoke a lot about government reform, and in effect, today marks the beginning of true government reform.”

“In view of the challenges we’re facing, we need responsibility on a national level,” the foreign minister added. “No more slivers of parties — fads that come together for a single term and then dissipate. We’re providing a true alternative, and an opportunity for the citizens to stabilize leadership and government.”

Liberman served as the director-general of the Prime Minister’s Office during Netanyahu’s first term as prime minister in the late 1990s, but then set out on his own to form Yisrael Beytenu, a party with particular appeal to voters from the former Soviet Union. Himself an immigrant from Moldova in the late 1970s, Liberman lives in the West Bank settlement of Nokdim and has charted a political course a little to the right of Netanyahu’s Likud in recent years.

Internal surveys were reported to have shown that the joint list would win more than 50 seats in the upcoming elections, a total unheard of by a single party in decades, and one that if realized would virtually guarantee Netanyahu continuing as prime minister in the next parliament, no matter which candidates ran and no matter which alliances were formed against him.

In the current 120-seat Knesset, Kadima is the biggest party, with 28 seats, followed by the Likud, with 27. A resurgent Labor Party, which has eight seats in the outgoing parliament, has been predicted in most opinion polls to become the second biggest party to the Likud after the elections.

In recent months, some voices on the left have called for former prime minister Ehud Olmert to throw his hat into the ring, arguing that he was the only candidate who had a real shot at dethroning the popular Netanyahu. First reports suggested the new partnership was hatched in part to counter the possibility of pro-Olmert momentum prompting shifts in public voting inclinations.

In the current Knesset, the two merging parties hold 42 seats between them — Likud 27, and Yisrael Beytenu 15. Analysts speculated that their joint slate would be built on a basis proportionate to the two parties’ current Knesset status — with approximately two out of every three slots for the Likud.

The merger with Yisrael Beytenu marked the second party-partnership bombshell dropped by Netanyahu in recent months. In May, in a late-night move when the Knesset was about to vote for early elections, he announced a merger with Shaul Mofaz’s Kadima and built a new coalition. That partnership collapsed after less than three months, however, setting in motion the process that ultimately led to the scheduling of elections for January 2013.

On Thursday, Netanyahu recalled his ill-fated coalition with Mofaz.

“Experience has taught me,” he said, “that a broad coalition without the earnest will for cooperation can’t guarantee governability and stability. Israel is better off with a strong coalition led by a large, cohesive [Knesset] list that is founded on true partnership.”