ELI, West Bank — Singing and dancing greeted a triumphant Benjamin Netanyahu when he visited Eli, then a young settlement of 959 residents, shortly after first becoming Israel’s prime minister in 1996. “We will be here permanently forever,” he declared in nearby Ariel that day, promising to renew the internationally contentious construction of Jewish communities across the land Palestinians plan as their future state. Struggling for settlers’ support ahead of Israel’s March 17 elections, Mr. Netanyahu returned last month to Eli, now a boomtown of more than 4,000 people that sprawls across six hilltops amid Palestinian villages and farmland. This time, he did not speak about new building, but his presence was a statement in itself: Eli is among dozens of isolated settlements whose expansion and entrenchment threaten the prospects of a two-state solution to the Israeli-Palestinian conflict. Steady growth of settlements across the occupied West Bank and East Jerusalem, which most world leaders consider violations of international law, complicates both the creation of a viable Palestine and the challenge of someday uprooting Israelis, who are now raising a second and third generation in contested areas. Along the road from Eli to Ariel one recent afternoon, a Palestinian man grazed a few cows and sheep on a grassy hillside, and scores of teenagers in white Islamic head scarves walked home from school. Inside the settlement’s gate, where a new shopping complex opened last year, bulldozers were at work on construction of a $3.8 million, 300,000-square-foot community center. A sign at the entrance announced, “Eli: A Big Place to Grow.”

As Mr. Netanyahu seeks a fourth term, his record on settlements is a central element of his troubled relationship with Washington, alongside the divergence on how to deal with Iran’s nuclear program. Construction in the West Bank is also at the heart of mounting European criticism of Israel. In the campaign, Mr. Netanyahu is navigating between his center-left challenger, Isaac Herzog, who promised to freeze construction beyond the so-called settlement blocks near Israel’s pre-1967 lines, and rightists who say the prime minister has not built nearly enough. An analysis of planning, construction, population and spending data over the past two decades shows that Mr. Netanyahu was an aggressive builder during his first premiership in the 1990s, when the West Bank settler population rose at roughly three times the total Israeli rate. But since returning to Israel’s helm in 2009, Mr. Netanyahu has logged a record similar to the less-conservative leaders sandwiched between, with those settlements swelling about twice as fast as Israel overall.

Annual population growth of West Bank settlements Benjamin Netanyahu Ehud Barak Ariel Sharon Benjamin Netanyahu Ehud Olmert 8% 6% 4% 2% ’96 ’97 ’98 ’99 ’00 ’01 ’02 ’03 ’04 ’05 ’06 ’07 ’08 ’09 ’10 ’11 ’12 ’13 Source: Israeli Central Bureau of Statistics Annual population growth of West Bank settlements 2% 8% 4% 6% ’96 Benjamin Netanyahu ’97 ’98 ’99 Ehud Barak ’00 ’01 Ariel Sharon ’02 ’03 ’04 ’05 ’06 Ehud Olmert ’07 ’08 ’09 ’10 Benjamin Netanyahu ’11 ’12 ’13 8% 2% 4% 6% Source: Israeli Central Bureau of Statistics In those recent years, however, Mr. Netanyahu has taken several steps that make drawing a two-state map particularly problematic, and has declared: “I do not intend to evacuate any settlements.” He has taken more heat over settlements than his predecessors, analysts said, in part because of his broader intransigence on the Palestinian issue and the use of construction as a retaliatory tool. But Mr. Netanyahu is also a focus of international ire because of the cumulative effect of decades of settlement growth. With negotiations stalled between the Palestinians and Israelis, the number of settlers in the West Bank now exceeds 350,000 — including about 80,000 living in isolated settlements like Eli and Ofra that are hard to imagine remaining in place under any deal. In addition, there are another 300,000 Israelis living in parts of Jerusalem that Israel captured from Jordan in the 1967 war and later annexed in a move most of the world considers illegal. “The reality of all those years of construction, to which Netanyahu is now adding his significant share, has created a sense of urgency and of panic,” said Aaron David Miller, who advised six American secretaries of state on the Middle East.

Construction starts in West Bank settlements Benjamin Netanyahu Ehud Barak Ariel Sharon Ehud Olmert Benjamin Netanyahu 4,000 3,000 2,000 1,000 ’96 ’97 ’98 ’99 ’00 ’01 ’02 ’03 ’04 ’05 ’06 ’07 ’08 ’09 ’10 ’11 ’12 ’13 ’14 Source: Israeli Central Bureau of Statistics Construction starts in West Bank settlements 1,000 2,000 3,000 4,000 ’96 Benjamin Netanyahu ’97 ’98 ’99 Ehud Barak ’00 ’01 Ariel Sharon ’02 ’03 ’04 ’05 ’06 Ehud Olmert ’07 ’08 ’09 ’10 Benjamin Netanyahu ’11 ’12 ’13 ’14 1,000 2,000 3,000 4,000 Source: Israeli Central Bureau of Statistics “Each of those other prime ministers who were builders were also able to placate Washington and cooperate with it because they were involved in some significant effort to actually negotiate and conclude an agreement. Netanyahu has drawn a blank or a zero on that,” Mr. Miller added. “If you have no strategy, and what you’re doing is increasing settlement activity, the perception is, frankly, that you’re not serious.” First elected in 1996 on a promise to reverse a four-year freeze on settlement expansion in all but a few areas, Mr. Netanyahu endorsed the concept of two states for two peoples upon regaining Israel’s top job in 2009, saying in his famous Bar Ilan speech: “We have no intention of building new settlements or of expropriating additional land for existing settlements.” Mr. Netanyahu now explains his building initiatives as an inevitable accommodation to natural growth and says they have not materially affected the map, only added, as he put it, “a few houses in existing communities.” He rebuts any suggestion that settlements are the core of the conflict, noting that Arabs and Jews were fighting in this land long before they existed. “From 1920, when this conflict effectively began, until 1967, there wasn’t a single Israeli settlement or a single Israeli soldier in the territories, and yet this conflict raged,” he said in a May interview with Bloomberg View. “What was that conflict about? It was about the persistent refusal to recognize a Jewish state, before it was established and after it was established.” Still, the American who led the latest round of failed Israeli-Palestinian negotiations, Martin S. Indyk, has said that Mr. Netanyahu’s “rampant settlement activity” had a “dramatically damaging impact.” The Palestinians plan to file a case in the International Criminal Court in April contending that settlements are a continuing war crime. A recent report from the anti-settlement group Peace Now showed that government-issued bids for building — the last of many steps that precede construction — have grown steadily since 2009 to reach 4,485 units last year. Two-thirds of new construction over the last two years, the Peace Now report shows, was on the Palestinian side of a line drawn by the Geneva Initiative, an international working group that produced a model agreement in 2003. “What I see is much more emphasis on construction in the most problematic settlements, which are the potential deal-breakers for a two-state solution,” said Hagit Ofran, director of Peace Now’s Settlement Watch project. “It was a taboo beforehand. The official policy of Israel was, we are not building new settlements, we are heading for peace. The Netanyahu government just left this policy.” Spending on settlement activity during Mr. Netanyahu’s current tenure averaged $252 million annually, according to reports that Israel is required to provide to Washington, compared with an average of $243 million in the six previous years. Another new study, from Israel’s Macro Center for Political Economics, found that the government spent about $950 supporting each West Bank resident in 2014, more than double its investment in people living in Tel Aviv or Jerusalem; in isolated settlements, it was $1,483 per capita.

The West Bank is 2,100 square miles of rolling hills, dotted by some 200 Jewish settlements surrounded by security fences. They include the city of Ariel, with its own university and regional theater; planned communities of cookie-cutter houses with red-tile roofs; and hilltop outposts where a few dozen people live in trailers. Most of the growth has been in three settlement blocks near Jerusalem and Tel Aviv slated for land swaps with the Palestinians in a future peace deal. But while Palestinian leaders have accepted the concept of swaps, neither they nor the United States have ever agreed on a delineation of such blocks.

WEST BANK Modiin Illit The biggest and fastest-growing settlement is Modiin Illit, an insular, ultra-Orthodox enclave just over the 1967 line that is widely expected to stay in Israel. In 2009, the community recorded 60 births a week; today, it has more than 60,000 residents.

Modiin Illit 1997 Aerial photography from Peace Now Most men in Modiin Illit study the Torah full time; hundreds of young mothers work in a decade-old business center providing paralegal research or credit-card customer service. Strollers often outnumber cars on the streets. The population in isolated settlements, which are outside anyone’s conception of blocks, has grown 15 percent since 2009 and is now double what it was when Mr. Netanyahu first took office in 1996. Mr. Netanyahu has repeatedly stated that he has not created any new settlements, but that is a question of semantics. Not far from Eli is a little place called Leshem, which opened two years ago with 104 families. The government calls Leshem a new neighborhood of the decades-old settlement up the road, Alei Zahav. But Leshem has its own kindergarten, its own community council and a website that pitches it as “a new and sparkling settlement.” More of its modular, flat-roofed beige homes — distinct from the signature red-tiled slopes of Alei Zahav — are under construction. There is an even bigger building boom a few miles east, in Bruchin, one of three outposts retroactively legalized in 2012 at the government’s prodding.

WEST BANK Bruchin Over the past six months, earth-toned stone walls have been erected in Bruchin to mark 50 suburban-style plots, increasing the settlement’s size by half. A dozen of the two-story homes are finished but for the siding and the paving of a new road; 100 families are on a waiting list to move in.

Bruchin 1997 Aerial photography from Peace Now Last month, Israel’s phone company started laying lines to connect the community, which was long off-limits. “We are now a small settlement,” said Yisrael Saadia, Bruchin’s manager. “We want to be a big settlement.” Back in 2005, the Israeli government itself identified about 100 outposts, including Bruchin, that had been established illegally. Since 2011, 19 of them have obtained government approval, and six more are in the pipeline, according to a forthcoming report by the Israeli group Yesh Din and the Rights Forum, which is Dutch. If such outposts are the most contested, one place where there is a broad consensus that settlements will stay is the Etzion block, stretching south from Jerusalem along Route 60. There were Jewish communities there before Israel’s establishment in 1948, and Mr. Herzog of the center-left Zionist Union recently campaigned in the block, declaring that “it must be part of Israel for eternity.” But in this area, too, Mr. Netanyahu’s initiatives have deepened the dilemma for peacemakers.

WEST BANK Efrat Efrat, with nearly 10,000 residents, is to Israelis the capital of the Etzion block. Palestinians, though, do not accept it as part of the block at all, because it is on the eastern side of Route 60 — their side of the Geneva Initiative map. Annexing it would be far more complicated. Yet over the past four years, tenders have been published for more than 1,100 new units in Efrat, and land cleared for a new neighborhood that would extend the settlement even further east. “What you’re doing is actually affecting the delineation of the blocks, but unilaterally,” said Gilead Sher, who heads a group, Blue White Future, that is pushing to evacuate some settlements and shore up others. Of Mr. Netanyahu, he added, “He speaks about the two-state solution, but he does whatever there is in his capability to delegitimize the two-state solution.”

The settlers themselves hardly see Mr. Netanyahu as a savior. His recent sojourn to Eli was to beat back a challenge from the rightist Jewish Home party, which won 71 percent of Eli’s votes in the 2013 election, compared with 13 percent for Mr. Netanyahu’s ticket. Settlers felt betrayed by his acquiescence, in 2009, to the Obama administration’s demand for a 10-month settlement freeze. Despite the drumbeat of settlement announcements that have outraged the world in the last two years, they complain that new plans have not advanced during that time. Dani Dayan, a leader of the settler council, said Mr. Netanyahu sees settlements as “a tool of policy,” not as a matter of principle, and has “good intentions” but “doesn’t always translate them into acts.” “Like many other issues, Netanyahu is in favor, but he’s the master of maneuver,” Mr. Dayan said. “I cannot say there was a strategic change by Netanyahu. He left the situation more or less like it was six years ago, in a somewhat larger scale.” Early in his first term Mr. Netanyahu signed the Hebron agreement, withdrawing Israelis from 80 percent of the biblical city, something Mr. Dayan said settlers perceive as his “original sin.” Around the same time, though, he approved Har Homa, a new neighborhood in southern Jerusalem that the Palestinians — along with the United States and Europe — contested fiercely for blocking access between Bethlehem and East Jerusalem, which they claim as their future capital. “Write it down,” he said in 1998. “You will see houses at Har Homa, many houses, by the year 2000.”

WEST BANK Har Homa Har Homa has more than 25,000 residents today. They live in stone apartment blocks studded by modern playgrounds, drawn by bigger spaces for less money than are available elsewhere in the city. A listing for a five-bedroom apartment with two balconies (asking price $611,000) includes “views over Bethlehem” as a prime selling point.

Har Homa 1997 Aerial photography from Peace Now Mr. Netanyahu also irked Washington in 1997 by adding 300 new homes in Efrat. Speaking of the entire West Bank, he said that year: “This is the land of our forefathers, and we claim it to the same degree that the other side claims it.” Since retaking office in 2009, Mr. Netanyahu has somewhat softened his public stance. “Of course some settlements won’t be part of the deal; everyone understands that,” he said a year ago. But he has also described Ariel, perhaps the most contested part of the blocks, as the “heart of our country.” And he has promised to “strengthen the Jewish settlement in Hebron” — fighting words to the Palestinians.

“What is preventing a solution to the conflict is the refusal to recognize Israel as the state for the Jewish people, certainly not building in Gilo," Mr. Netanyahu said in 2013, referring to a Jerusalem neighborhood near Har Homa. “Does anyone think that Gilo will not stay as part of Israel?” It was the announcement of 700 new apartments in Gilo that Secretary of State John Kerry saw last year as the last straw that scuttled his peace initiative: “Poof, that was sort of the moment,” he said afterward. Mr. Netanyahu shrugged it off, saying a few months later: “The French build in Paris, the English build in London and the Israelis build in Jerusalem.” But here in Eli, where campaign banners for the Jewish Home outnumber those for the Likud, the mayor says the settlement has grown despite the government, not because of it.

Children played in Eli, an Israeli settlement in the West Bank. Eli sprawls across six hilltops amid Palestinian villages and farmland. A few months ago, 64 families moved into Eli’s first four-story apartment buildings. Next on the drawing board: six stories, with elevators. But Eli’s three schools remain in trailers, lacking approval for construction. After-school activities for 600 children, a library used daily by 300 families, and yoga and ceramics classes for older residents all take place in bomb shelters. “Every brick we want to move, it’s a fight,” said Nitza Farkash, one of the settlement’s 25 employees. Named for a biblical high priest, Eli opened in 1984 and has become the heart of what Israelis call religious Zionism, with a 500-student pre-military yeshiva where Mr. Netanyahu recently spoke in a room lined with Talmudic texts. An aerial photograph from 1997 shows half of its six hilltops barren; now they have homes, synagogues and sports fields. The mayor, Kobi Eliraz, says Eli covers 1,500 acres, double its 1997 footprint. “All the years we thought big — not like a small town. We want to be a big city,” he said as he drove along Eli’s 15-mile ring road. “From when there was a single caravan here, the founders that came, they had a big view and a big vision to see all Eli like Tel Aviv.”