JERUSALEM — Prime Minister Benjamin Netanyahu of Israel on Sunday called for early elections, vowing to win a “renewed mandate” and “form the broadest government that is possible” to “guarantee the future of the people of Israel in the land of Israel, for eternity.”

“Political instability always leads to extortion and populism that undermine the defense and social economy, and I will not lend a helping hand to an election campaign that will stretch over the course of a year and a half and hurt the country,” Mr. Netanyahu, 62, said in a brief speech, responding to stirrings in recent weeks among his coalition partners and his opponents.

“It is better to have a short election campaign of four months that will restore political stability,” he said.

The speech, delivered at the annual convention of Mr. Netanyahu’s right-leaning Likud Party in Tel Aviv, was the prime minister’s first public appearance in a week, following the death of his father. But the plan for early elections has been obsessively discussed here for days, and Parliament was expected to dissolve itself on Monday, with the popular vote scheduled for Sept. 4, rather than October 2013.

The official pretext is the court-mandated expiration of the Tal Law, under which vast numbers of ultra-Orthodox Jews were exempted from Israeli Army service; Mr. Netanyahu’s coalition government is split over the draft issue, and dissolving it avoids a messy fight and postpones the deadline for rewriting the law.

But analysts have offered myriad theories on Mr. Netanyahu’s motivations. Many believe he wants a strong vote of confidence before the presidential elections in the United States, while some speculate he is considering an October strike against Iran’s nuclear facilities. Others see more pragmatic explanations for his timing: with sky-high approval ratings and a divided opposition, moving quickly could give the incumbent an extra edge.

“The earlier you go, the less chance the new competitors have to get organized,” said Peter Y. Medding, a political scientist at the Harman Institute of Contemporary Jewry at Hebrew University.

Recent polls show Likud winning 30 to 32 of the Parliament’s 120 seats, nearly twice that of its closest competitor, the leftist Labor Party; several centrist and conservative parties would take anywhere from 10 to 15 seats, according to the surveys.

Right now, the opposition is split among Shelly Yacimovich, who leads Labor and has capitalized on last summer’s social protest to make economic inequality her signature issue; Shaul Mofaz, who recently took over the centrist Kadima Party and, as a former defense minister and military chief, has strong security credentials; and Yair Lapid, a popular television host who just formed a new party, Yesh Atid (There is a Future), which focuses on bread-and-butter issues and the question of drafting the religious.

“There’s no clear leader and there’s no clear agenda,” Aluf Benn, editor of Haaretz, a daily paper frequently critical of the Netanyahu government, said of the fractured landscape. “We tend to say the opposition never wins the election, it’s the incumbent government that loses the election. I don’t see the eagerness to oust him. People feel he is the only one capable of doing the job.”

Tamar Hermann, a senior research fellow at the Israel Democracy Institute who specializes in public opinion, agreed that Mr. Netanyahu is “right now the only person who can be defined on the grass-roots level as a national leader.” But Ms. Hermann said his strength is in security and foreign policy, and she expects the campaign to focus more on domestic concerns, including political corruption, public housing, the cost of living and questions of religion and state.

Indeed, at a campaign event on Saturday night in Tal Shahar, north of Jerusalem, Mr. Lapid, 48, barely mentioned the peace process until asked about it by the audience of 120, and said nothing about Iran. Instead, he talked about improving schools, helping young couples buy their first apartments, reducing wait times at emergency rooms, integrating the ultra-Orthodox into society and overhauling government to reduce corruption.

“We forgot that we’re not a sector, we are the majority,” said Mr. Lapid, referring to the political center. “Everybody thinks that it’s just them and their friends. We have to think like the majority.”

Mr. Netanyahu also addressed kitchen-table issues, but he got his biggest cheers when he mentioned the return of the captured Israeli soldier Gilad Shalit, and repeatedly hit the security theme.

“It was only a few years ago that people did not feel safe in this country, and today the situation is different,” he said, adding, “Thanks to our activities, the world now has enlisted itself against the Iranian nuclear program, and this pressure will not be lifted until the threat is truly removed.”

Mr. Netanyahu continued, “We will look for every opportunity to promote true peace with our neighbors, and we will defend our nation’s vital interest, just as we have been doing.”