JERUSALEM — Israeli Prime Minister Benjamin Netanyahu and the centrist opposition party Kadima formed a surprise unity government Tuesday, extinguishing plans for early elections and cementing Netanyahu’s position as the strongest Israeli leader in years.

The deal gives the governing coalition a vast parliamentary majority, fortifying Netanyahu’s mandate as he presses for possible military action against Iran’s nuclear sites, an idea that has faced growing domestic criticism. It could also shift the hawkish coalition toward the center, granting Netanyahu room to weather threats of revolt by right-wing factions and perhaps leeway to offer concessions to the Palestinians.

The announcement of the secretly negotiated deal appeared to stun even senior Israeli officials, who hours earlier had been moving to dissolve parliament and prepare for early elections in September. Netanyahu, whose Likud party had been expected to win easily, said Tuesday that the agreement with Kadima leader Shaul Mofaz allowed him to swiftly deliver what he had pledged to create after the elections — a broad-based alliance that would ensure stability.

“I realized that it was possible to restore stability without holding elections,” Netanyahu said at a joint news conference with Mofaz. He called the deal “good for security, good for the economy and good for the people of Israel.”

The agreement triggered a new round of speculation about the chances of an Israeli strike on Iran’s nuclear program, which Israel deems an existential threat. Some commentators said the deal meant that Netanyahu had cleared his calendar to prepare for war. Others said the sudden ascent of Mofaz, a former military chief and defense minister who has expressed opposition to a unilateral Israeli attack, made war less likely.

Neither man shed much light on the subject Tuesday, saying only that they would discuss it seriously. In any case, some observers said, the new coalition’s majority — 94 out of 120 seats in parliament — would give new muscle to Netanyahu’s push for tough action against Iran, allowing him to say more firmly than ever that he represents the Israeli point of view.

“The decision that has been taken last night sends a very clear message that this is the prime minister and this is the government which people will have to deal with for a long time,” said Zalman Shoval, a former ambassador to the United States and longtime adviser to Netanyahu. “And this is a message both to our friends and to our foes.”

Political considerations

The immediate aim of the deal, under which Mofaz became a vice prime minister, is to push through a replacement for a law that exempted ultra-Orthodox seminary students from military duty, an issue that had divided Netanyahu’s coalition. The alliance was also split over court-
ordered evacuations of West Bank settlements, and right-wing Likud members had sought to oust Netanyahu’s key partner on the Iran issue, Defense Minister Ehud Barak, who oversees such evacuations.

“It makes the makeup of the government more centrist and representative of the whole gamut of Israeli society,” Dan Meridor, a deputy prime minister, said in an interview. “We have more flexibility in making decisions and not being dependent on small parties with special agendas.”