When 18,000-plus activists meet in Washington for AIPAC’s annual pro-Israel hootenanny March 1 through 3, many of the usual Israel speakers, including top politicians, won’t attend – thanks to Election Day 3.0. Most US presidential candidates won’t show up – because of Super Tuesday. But most absent – and most dismaying – will be the bipartisan spirit, which has been the pro-Israel movement’s calling card.This is an American problem that goes far beyond US-Israel relations. Increasingly, our age of fanatic partisanship considers bipartisanship delusional or distracting. Too many conservatives justify anything President Donald Trump does, no matter how reprehensible, because he’s their guy. Too many Never, Ever Trumpers repudiate everything he does, even if it’s reasonable, because he’s their enemy. If Fox conservatives believe bipartisanship is for wimps, Sen. Bernie Sanders liberals believe it’s for sellouts.With most American Jews occupying the Trump-hating-left, the newly emerging liberal critique of bipartisanship merits extra attention. Increasingly, some progressives misread American history, claiming that calls for bipartisanship, civility, consensus and compromise perpetuated the slaveocracy, racism and other abuses. They believe these values and tools only serve the status quo. They fail to explain the broader historical mystery of how America progressed. In fact, while revolutionaries and abolitionists, America’s Martin Luther Kings and Betty Friedans, sparked change, bipartisan cooperation, civil debate, consensus-building leaders and visionary compromises transformed the radical ideas into mainstream reforms.If the impeachment fight proves how polarized partisans are when assessing Trump’s personal behavior, the fight over Israel increasingly proves how polarized partisans are when assessing Trump’s policies. The Republican senators’ loyalty confirmed Trump’s 2016 campaign boast that he “could stand in the middle of 5th Avenue and shoot somebody” without losing any supporters. In response, many anti-Trumpers are so furious, it seems he could come to Jerusalem, deliver peace with a big golden “T” emblazoned on it – without winning over any critics.Amid such polarization, slavishly celebrating America’s bipartisan support for Israel without addressing the underlying threats to bipartisanship, is like planning a nature trip to the Australian bush without noticing the wildfires.Israel still enjoys bipartisan approval – 70% of Americans remain pro-Israel. For this now-threatened status quo to persist, AIPAC and other forces cherishing civility and bipartisanship in America must champion those values too, while AIPAC and others who care about keeping the Democratic Party pro-Israel must figure out how to resist the haters too.Instead, too many have insisted there’s no problem – overlooking the dramatic warning signs. Last year, House Majority Leader Steny Hoyer proclaimed at AIPAC that “there are 62 freshman Democrats – you hear me? Sixty-two not three.” But while reaffirming that which still is, worry about what might soon be.The “three” Hoyer targeted – Reps. Alexandria Ocasio-Cortez, Rashida Tlaib and Ilhan Omar – are radicals who oppose Israel and bipartisanship. AOC insists that even before Trump, “bipartisanship was s***ty.” But more and more, the same Democrats who reject bipartisanship as “disastrous,” as “ruining America,” as perpetuating power, also demonize Israel. Former Vermont governor Howard Dean claims Israel “embraces ethnic cleansing.” Sen. Elizabeth Warren says “yeah” when a voter claims AIPAC is in an “unholy alliance… with Islamophobes and antisemites and white nationalists.”More broadly – and worryingly – many Democratic presidential candidates threaten to blackmail Israel with military aid. And most Democrats refused even to read Trump’s “Deal of the Century” thoughtfully, to see if it offered anything positive.CURRENTLY, ISRAEL risks going from being a popular punching bag for some, to the progressive’s universal, defining, virtue-signalling punch line. It happened on the European Left – it could happen in America too.Responding aggressively won’t work because too many Democrats protect their left flank like Republicans protecting their president. AIPAC’s recent warning that: “The radicals in the Democratic Party are pushing their antisemitic and anti-Israel policies down the throats of the American people” backfired. Predictably, AIPAC backpedaled, apologizing for telling the truth about the few “radicals” – who aren’t the majority.And beware, celebrating Israel’s tastiest cherry tomatoes, greatest inventions or latest billion-dollar-exits may please the convention center crowd but won’t still the doubters or sway the uncommitted.Winning this critical power struggle requires winning the battle of ideas. AIPAC must double down, teaching about Zionism and why the Jews deserve a state, and about Israeli history and why Israel deserves a break. But, as with the universities, first, spearhead the broader American debate advocating liberal – not Trumpian – nationalism, regardless of where you stand politically; and spreading the values of those who choose unity – especially bipartisanship, civility, consensus, and compromise.In Why Nationalism, a founder of Peace Now, Yuli Tamir, justifies nationalism from the Left, saying only the nation-state can create the kind of “cross-class coalitions” necessary “to promote a more just social order.” Similarly, in The Atlantic, Harvard political philosopher Danielle Allen recently echoed George Washington’s call to “choose unity,” as a “moral” stance to resist “bullying… tyranny… and gridlock”: An “unswerving insistence on unity – induces citizens to seek out ways of adapting their purposes so as to get something done,” Allen explained. “Because if unity is not negotiable, then there is no other choice.”Indeed, a commitment to unity – among Jews, among Americans, between Americans and Israelis, moderates, centers, anchors us. Without that self-discipline, we will continue indulging our anger. So just as during the Cold War and the War on Terror, uniting behind Israel reinforced America’s national security, during this intensifying domestic civil war, uniting behind Israel expresses the liberal nationalism essential for America’s national soul.The writer is the author of The Zionist Ideas, an update and expansion of Arthur Hertzberg’s classic anthology, The Zionist Idea, and a 2019 National Jewish Book Award finalist. A distinguished scholar of North American history at McGill University, he is the author of 10 books on American history, including The Age of Clinton: America in the 1990s.