Israeli Prime Minister Benjamin Netanyahu talks as he visits a construction site in Har Homa in East Jerusalem. Netanyahu said that as long as he remains Israel's leader, a Palestinian state would not be established. (Olivier Fitoussi/AP)

On the final day of his reelection campaign, Benjamin Netanyahu said that as long as he serves as prime minister of Israel, there will not be an independent Palestinian nation.

His declaration marks the second time in a month that Netanyahu has chosen to confront Washington directly: first by opposing, in a speech before Congress, President Obama’s possible deal to try to curtail Iran’s nuclear ambitions and now by opposing a two-state solution to the Israeli-Palestinian conflict, which Secretary of State John F. Kerry spent nine months pursuing.

Netanyahu’s assertion, made on camera to an Israeli news Web site, appeared to reverse the prime minister’s previous declarations of support for a sovereign Palestinian state.

“I think that anyone who is going to establish a Palestinian state today and evacuate lands is giving attack grounds to the radical Islam against the state of Israel,” he said in a video interview published Monday on the NRG site.

“Anyone who ignores this is sticking his head in the sand. The left does this time and time again,” Netanyahu said. “We are realistic and understand.”

Netanyahu was then asked specifically whether he meant that a Palestinian state would not be established if he were reelected prime minister. He answered, “Correct.”

In a speech at Bar-Ilan University in 2009, Netanyahu famously said that he supported a two-state solution to end the Israeli-Palestinian conflict, as long as Israeli conditions were met and Israel’s security was guaranteed. That speech and two rounds of U.S.-brokered peace talks since then led many to assume that the prime minister was prepared to see a Palestinian state arise in the West Bank and Gaza Strip.

On Monday, Americans and ­Israelis were left unsure whether Netanyahu was just speaking off the cuff during an interview in the heat of a very close race or whether he was signaling a real change in policy.

State Department spokeswoman Jen Psaki declined to comment except to say, “There are many things said leading up to elections.’’ She added: “Obviously, our view continues to be that the only way to have peace and stability in the region is for there to be a two-state solution.”

Erel Margalit, an opposition leader in the Labor Party, called Netanyahu’s statements “outrageous.”

“It undermines the direction that Israel has declared it is striving for during the last three prime ministers,” Margalit told The Washington Post. “We need to build trust with the Palestinians again and make sure they do not continue with their unilateral steps.”

Saeb Erekat, who was the chief Palestinian negotiator during the Kerry peace talks, said he was not surprised to hear the remarks. “Netanyahu has done everything possible to bury the two-state solution,” he said. “This is not something new to us.”

Netanyahu’s words hit the Internet soon after the prime minister visited a Jewish settlement in East Jerusalem on Monday and warned that if it were not for him and his right-wing Likud party, residents there would be next-door neighbors with the ­Islamist militant movement Ha­mas.

At a news conference at which journalists were not allowed to ask questions, Netanyahu stood at a lectern on the terrace of Yaron and Sigal Hakoshrein’s new condominium, framed by building cranes over his shoulder, towering above units under construction.

Netanyahu called his host to stand beside him and asked on camera, “Do you want to see Hamastan over there on that mountaintop?” He then pointed in the general direction of Bethlehem, the Palestinian city in the West Bank where the Bible says Jesus was born.

Yaron Hakoshrein, a Likud activist, shook his head and said no.

“Then there is only one answer. Then you have to put the voting slip for Likud in the ballot box,” Netanyahu said.

The message was not subtle — but it sure was direct.

Israelis who fear that Hamas will take over the West Bank, as it did the Gaza Strip in 2007, have adopted the shorthand “Hamastan” to express that concern. Hamas is branded a terrorist organization by Israel and the United States. Israel and Hamas fought a 50-day war last summer.

On Sunday night, Netanyahu warned supporters at a rally in Tel Aviv that he may not win Tuesday’s election, a potentially dramatic fall for a consummate political survivor whose nine years in office transformed him into the public face of contemporary Israel.

The final round of opinion polls Friday showed Netanyahu and his Likud party facing a surprisingly strong challenge by Isaac Herzog, leader of the center-left Labor Party, and his running mate, former peace negotiator Tzipi Livni, who hold a small but steady lead.

For the past five days, Netanyahu has been working to bulk up support among members of his nationalist right-wing base, warning Israelis that his challengers would “give away land for peace” to the Palestinians, would divide the “eternal capital of ­Israel” and would turn over the eastern sections to the Palestinians for a future state.

Netanyahu has vowed “no concessions” and “no withdrawals” from the West Bank in speeches and statements during the campaign.

Over the past quarter-century, Israel and the Palestinians have engaged in many talks that failed to bear fruit. Kerry’s attempt collapsed last April, with each side blaming the other.

In a statement issued by his Likud party a week ago, Netanyahu was quoted as saying that his past support for an independent Palestinian state is now irrelevant.

“In the Mideast today, any evacuated territory will be overtaken by radical Islam and terror groups backed by Iran. Therefore, there will be no withdrawals and no concessions. It’s just not relevant,” the statement read, attributing the remark to Netanyahu.

Afterward, Netanyahu’s spokesman attempted to clarify matters by stating that the prime minister meant to say that “under current conditions in the Middle East, any land that is handed over would be grabbed by Islamist extremists.”

The Palestinian Authority under President Mahmoud Abbas, which oversees part of the Israeli-occupied West Bank, has vowed to pursue a path of nonviolence and has coordinated its security responsibilities with Israeli forces.

Netanyahu’s campaign staged its Monday news event at the Jewish settlement of Har Homa in East Jerusalem for a reason. During his first term as prime minister, Netanyahu approved construction there.

Netanyahu said settlement construction at Har Homa was not only to provide housing for residents but also to deny Palestinians territory and contiguity.

Jewish settlements in the West Bank and East Jerusalem are considered illegal under international law. U.S. diplomats prefer to call the settlements “illegitimate.” The Israelis dispute that.

“It’s a neighborhood that I initiated in 1997 in my first stint as prime minister,” Netanyahu said. He said its value is that “it stops the continued advancement of the Palestinians.’’

Ruth Eglash contributed to this report.

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