The divided loyalty smear — the wormy old question of whether Jews anywhere can truly be counted upon to support their own government, as opposed to Israel or some larger worldwide conspiracy — is a classic accelerant of anti-Semitism.
Generally, it's a question posed throughout history by nativist or outright racist groups and parties on the extreme right.
Jewish leaders in the diaspora, knowing the destructive power of what usually amounts to a false choice, are generally careful to avoid it.
But in modern America, where politics is mostly a bitter shouting match, the false-choice gambit is just another partisan tool. The surprising thing this time is who's using it.
American Jews awoke Monday to discover that Israeli Prime Minister Benjamin Netanyahu now presumes to speak not just for his own citizens, but for all of Jewry.
He intimated as much on Sunday when he defended his increasingly contentious plan to address the U.S. Congress next month over the clear objections of the White House.
Netanyahu is fighting to keep his job in a tight election campaign at home, and a key plank is to thwart the Obama regime's negotiations with Tehran, which are intended to limit Iran's nuclear capabilities.
In trying to bring this about, Netanyahu has blatantly chosen the Republican camp.
His ambassador to Washington, an American-born former Republican operative named Ron Dermer, arranged directly with the Republican leadership for Netanyahu to address Congress on March 3, two weeks before the Israeli election.
Dermer has said publicly he saw no need to notify the White House, which has described the affair publicly as a breach of diplomatic protocol and privately as Netanyahu spitting in Obama's face.
Netanyahu wants to use the speech to warn that Iran cannot be trusted, and that any deal the Obama administration might secure will only provide its mullahs with more time to build a bomb.
To Netanyahu, and congressional Republicans, the only proper approach to Iran is more sanctions.
But the very idea of an Israeli prime minister speaking out against the U.S. president from the well of Congress has provoked an uproar that's unsettled some American Jewish leaders, even those who have also made Iran their priority issue.
Several members of Congress, including some who are Jewish and pro-Israel, have spoken out against the planned speech. At least 12 Democrats, including Vice-President Joe Biden, one of the most outspokenly pro-Israel politicians in the country, have announced they will not attend.
Obama intends to ignore Netanyahu during his visit.
Such prominent American Jews as Abraham Foxman, leader of the Anti-Defamation League has said the speech should be cancelled, calling it a "tragedy" that politicizes Israel's relationship with America. It is impossible to get more pro-Israel than Foxman.
Even AIPAC, the influential pro-Israel lobby in Washington, has kept a careful distance from the event.
In Israel, several political leaders, some of them past allies of Netanyahu, have agreed with Foxman. Three Israeli diplomats have been recalled to Jerusalem for tweeting denunciations of the speech.
Bradley Burston, a U.S.-born Israeli writer, asked in the newspaper Ha'aretz how Netanyahu could dare claim to represent American Jews, most of whom voted for Obama, "in part because of Barack Obama's role in fostering security co-operation with Israel, including additional funding for the Iron Dome rocket defence system."
Still, Netanyahu has barged ahead.
Battle lines being drawn
And the Israeli leader's Republican allies here have lined up behind him, threatening to punish members of Congress who don't attend the speech.
The Zionist Organization of America has compared Foxman to Jews who counselled caution in dealing with the Nazis. (Foxman is a Holocaust survivor).
Matt Brooks, executive director of the Republican Jewish Coalition, has declared that the choice facing all members of Congress, and by implication, their voters, is this:
"To stand with Israel and Prime Minister Netanyahu" or choose "partisan interests and stand with President Obama."
Stand with your president, or a foreign leader. A clumsier framing of any issue is impossible to imagine.
At the other end of the spectrum, Yossi Sarid, a giant of Israel's political left, replied with disgust that "Benjamin Netanyahu is determined to show the president once and for all who really rules in Washington, who is the landlord both here and there."
In the short term, Netanyahu's tactics, and even the speech, may work for him. He has probably gathered more of the right-wing vote in Israel's multiparty system.
But the last Israeli leader to tangle publicly with an American president, Yitzhak Shamir, lost his next election. Generally, Israelis understand that the American president has always been Israel's best friend — a recent poll suggests half of Israelis want Netanyahu to back off.
And, in any event, Netanyahu has failed, rather spectacularly, to foil Obama's negotiations with Tehran.
The multi-government negotiations with Iran look to be nearing a conclusion, and Obama has said he will veto any effort by Congress to step up sanctions, which the White House feels would disrupt everything that's been accomplished to date.
That's not to say an agreement with Tehran will happen. Obama also said this week he will not agree to another extension of the talks, and if they fail, he will certainly support more sanctions.
But an overwhelming majority of Americans support Obama's efforts to secure a deal, if polls are accurate.
Netanyahu, meanwhile, tweeted on Tuesday that he remains resolute: He will come to America and effectively advise Americans who support their president they are wrong.
And remind Jewish Americans that in his mind at least, it is he, and not their president, who truly speaks for them.