Benjamin Netanyahu has had his share of run-ins with the White House through the years. But his public outburst earlier this week over America’s unwillingness to issue an ultimatum to Iran has prompted some of the harshest American criticism of an Israeli leader in decades.

The censures include a sharply worded letter from a U.S. senator, a withering editorial by the former executive editor of The New York Times, and a raft of other denunciations from analysts and officials, including those ordinarily sympathetic to Israel’s positions.

The common thread in much of the commentary: that Netanyahu is maligning President Obama (though not by name) in order to influence the outcome of the U.S. election in favor of Mitt Romney, the Republican candidate.

While Netanyahu denied the charge and has since softened his tone, the episode marked further deterioration in his relationship with the U.S. administration, and it could well have adverse consequences for the Israeli leader if Obama is reelected in November.

“It appears that you have injected politics into one of the most profound security challenges of our time—Iran’s illicit pursuit of nuclear weapons,” wrote Barbara Boxer, the Democratic senator from California, in a note addressed to Netanyahu’s office.

“I am stunned by the remarks that you made this week regarding U.S. support for Israel. Are you suggesting that the United States is not Israel’s closest ally and does not stand by Israel? Are you saying that Israel, under President Obama, has not received more in annual security assistance from the United States than at any time in its history?” she wrote, striking a tone that is almost never heard on Capitol Hill when it comes to Israel.

Senator Boxer was referring to Netanyahu’s remarks at a Jerusalem ceremony earlier this week, where he condemned the “international community” for failing to specify red lines that, once crossed, would prompt a U.S. strike on Iran’s nuclear facilities. Because Secretary of State Hillary Clinton had rejected the idea of issuing ultimatums just a day earlier, Netanyahu’s statement was seen as directed at the United States.

“The world tells Israel, ‘Wait, there’s still time’,” Netanyahu said ahead of a meeting with Bulgaria’s prime minister. “And I say, ‘Wait for what? Wait until when?’ Those in the international community who refuse to put red lines before Iran don’t have a moral right to place a red light before Israel.” His office later distributed the remarks to reporters.

Netanyahu has warned that Israel might attack the Iranian facilities if Obama fails to provide a firmer commitment for action against the program. (Iran says it’s developing peaceful nukes, a claim that most intelligence agencies reject.) Some analysts believe Netanyahu might strike before the U.S. election, at a time when Obama is more likely to rally for Israel—not wanting to alienate pro-Israel voters in key states like Florida.

But polls show most Americans don’t want the U.S. involved in a war against Iran. The White House has said more time is needed for sanctions against the regime to work.

The tension surged again this week after Israel said that Obama had declined to set a meeting with Netanyahu later this month when the Israeli leader travels to New York for the United Nations General Assembly gathering. Obama and Netanyahu have met nine times since the two were elected.

Bill Keller, who edited The New York Times until last year and remains an opinion writer with the newspaper, described Netanyahu’s behavior as a form of “crude intervention in our politics.” He said Obama, if reelected, is “unlikely to forget this exercise in manipulation by an Israeli leader he already has ample reason to mistrust.”

But Netanyahu defended the comments and said he had no intention of interfering in American politics. "It has nothing to do with the American elections, because the Iranian nuclear program doesn’t care about the American political calendar," he said in an interview with The Jerusalem Post that was to be published Friday.

“If the centrifuges stop miraculously, if they stop preparing enriched uranium to make atomic bombs, then I suppose I wouldn't have to speak out,” he said. “But the Iranian nuclear program proceeds unabated, and they don't care about the internal American political calendar. For me this is a policy issue, a security issue, and not a political issue.”