With all the shouting it was easy to miss, but something new happened in Washington this week. If you can’t see it yet, put yourself back in 2006, when everything about a Somali-American, Muslim congresswoman tweeting a line from a Puff Daddy song—as Minnesota Representative Ilhan Omar did Sunday evening—would have been unthinkable.

In March 2006, two established, neo-realist foreign policy wonks named John Mearsheimer and Stephen Walt published an article in the London Review of Books. They argued that outsized U.S. support for Israel, which receives more U.S. military aid than any other country on the planet, made little sense in a post–Cold War context in which Israel was no longer a “vital strategic asset.” Mearsheimer and Walt attributed the irrational persistence of this policy to highly effective lobbying efforts “to steer US foreign policy in a pro-Israel direction.” The Israel Lobby, as they called it, was not a cabal or a conspiracy, but something altogether ordinary in Washington, like the gun lobby or the steel lobby: a “loose coalition of individuals and organizations” encompassing Christian evangelicals, neo-conservatives, and the powerful America Israel Public Affairs Committee, whose support or opposition could make or break a candidate. “The bottom line,” they wrote, “is that AIPAC, a de facto agent for a foreign government, has a stranglehold on Congress, with the result that U.S. policy towards Israel is not debated there.”

To almost anyone with experience in American electoral politics, Mearsheimer and Walt were stating the obvious: The near unanimity of politicians’ support for Israel resulted not from inborn Zionist sympathies, but rather organizing and influence—which in Washington invariably involves money. The uproar was nonetheless fierce. Pundits lined up to get their kicks in. Jeffrey Goldberg, writing in The Atlantic, called the two authors “neo-Lindberghians” and characterized Walt as a “grubby Jew-baiter” who “makes his living scapegoating Jews.” David Rothkopf, in Foreign Policy, was only slightly more generous: While Mearsheimer and Walt “may not be anti-Semites themselves,” he allowed, “they made a cynical decision to cash in on anti-Semitism.” Jonathan Chait went after them repeatedly in the pages of The New Republic, dismissing their views as “simply kooky.”

By the time Ilhan Omar walked onto the national stage, a lot had changed, and not much at all. Since 2006, we’ve seen three devastating and overwhelmingly one-sided Israeli assaults on Gaza, the massive expansion of settlements in a brutal and seemingly endless occupation, the collapse of U.S.-sponsored peace negotiations and anything that could be called an Israeli “left,” a widening gulf between Israeli and American Jews, and an Israeli prime minister who went out of his way to embarrass a popular Democratic president and to embrace the neo-fascist right. Ever-larger cracks are appearing in the defensive wall the U.S. media has for years erected around Israel: Critical voices—even Palestinian ones—are increasingly making it into the op-ed pages. Space for debate is finally opening up. And the controversy that blew up around Omar is a foretaste of how bitterly that space will be contested.

It began, of course, on Twitter. Omar and fellow Congresswoman Rashida Tlaib both support the movement for Boycott, Divestment, and Sanctions (BDS) as a response to Israel’s occupation of Palestinian lands. On Sunday, House Minority Leader Kevin McCarthy threatened to “take action” against the pair. “This cannot sustain itself,” McCarthy had said. “It’s unacceptable in this country.”