He pointed to pictures of his three children, including a years-old photograph of his wife, Sally, with their youngest, now on active duty in the Israeli Defense Forces. “That little boy with his mother — there is my infantry officer now,” Mr. Oren said. “I’ve got these kids — their lives are on the line. The last thing we want is war. Part of our responsibility is seeking to avoid war. And if we can avoid war by raising international consciousness about the nature of the Iranian threat, then we’re fulfilling our responsibility.”

The nub of the tension between the United States and Israel is time: Mr. Netanyahu believes that the Iranians are so close to making a nuclear bomb that Israel soon will not be able to stop it, but the United States, with superior military capabilities, argues that it will be able to detect, and prevent, Iran from passing that point. Israel in turn says it cannot outsource its national security, even to an ally like the United States. Iran says its nuclear program is peaceful.

Like most Israeli ambassadors before him, Mr. Oren does not make policy, negotiate or carry vital messages between the two sides — the last a superfluous job when the traffic between the two administrations remains so intense. If Ehud Barak, the Israeli defense minister, needs to speak to the Obama administration, he picks up the phone and calls Defense Secretary Leon E. Panetta, Secretary of State Hillary Rodham Clinton and Thomas E. Donilon, the national security adviser. Or President Obama simply phones Mr. Netanyahu, as he did last week to try to calm the situation after the prime minister’s comments about red lines.

And Mr. Netanyahu has no problem communicating directly to the American public, as he demonstrated over the weekend by appearing on the NBC News program “Meet the Press” and CNN’s “State of the Union” to reiterate his warning that Iran is close to being able to produce a bomb.

Mr. Oren’s role is to shape and push Mr. Netanyahu’s point of view in Washington. As difficult as that is, he has the résumé to try. Raised in a conservative Jewish family in West Orange, N.J., Mr. Oren worked on a kibbutz at 15, was educated at Princeton and Columbia, immigrated to Israel and spent multiple tours in the Israeli Army, including a job as spokesman during an infamous low point for the military, its poor performance in the 2006 war in Lebanon. Along the way he wrote two highly regarded histories, one on the 1967 war, another on America’s turbulent 230-year relationship with the Middle East. He was appointed ambassador three years ago, giving up his American citizenship to do it.

Mr. Oren is unique among previous Israeli envoys in that he speaks American English, appears with fluency and frequency on television and writes dozens of op-ed articles for The New York Times and other newspapers. At the same time, Mr. Oren courts a wide network of reporters and columnists and speaks regularly to universities and Jewish groups, including now J Street, after he initially turned down an invitation to speak to them.

“I give him credit for coming to engage,” said J Street’s president, Jeremy Ben-Ami, whose group agrees with Mr. Oren that Iran is a threat but not that it is time to set a deadline.