In mid-1965, President Lyndon B. Johnson (LBJ) initiated the most sweeping program of domestic reform since Franklin D. Roosevelt’s New Deal. In carrying it through, however, he would make a grave mistake. As Johnson signed new legislation advancing civil rights, reducing poverty, and establishing Medicare, he dramatically ramped up America’s military involvement in Vietnam in the mistaken belief that doing so would inoculate him politically and allow him to maintain the support necessary to win reelection and continue to pursue his program.

Johnson’s greatest sin, of course, was not mere political miscalculation. Had escalating the slaughter in Vietnam somehow helped his reelection or strengthened the Great Society, it would still have been morally indefensible. But, as it turned out, Johnson’s decision didn’t help his domestic agenda or electoral prospects either. The Democrats took a beating in the 1966 midterms, losing forty-seven seats in the House and three in the Senate — a development that empowered Republicans and Southern Dixiecrats even as Democrats retained a formal majority. By 1969, with challenges mounting and the war growing increasingly unpopular, the president himself was ultimately compelled not to seek reelection.

The war, meanwhile, sapped both needed political energy and material resources from the Great Society. When Martin Luther King Jr gave an impassioned speech in April 1967 denouncing the conflict as a “demonic, destructive suction tube” that had pulled “men and skills and money” away from human needs in America, he was not only issuing a powerful statement of moral censure but acknowledging a basic material reality.

Though we would do well not to overstate the equivalencies between Johnson’s presidency in the 1960s and Joe Biden’s today —  no two wars are exactly the same and, though seriously compromised by Vietnam, Johnson’s domestic achievements far outstrip anything accomplished by Biden — there are some unmistakable parallels. Even before Hamas’s attack on southern Israel last month and the latter’s relentless bombing of Gaza, Biden was facing poor polling and increasingly vocal doubt within the Democratic Party about his prospects in 2024.

In the weeks since, however, things have gotten visibly worse. The latest polling shows Donald Trump leading Biden in five key battleground states (Georgia, Nevada, Arizona, Michigan, and Pennsylvania) and the president barely leading in one (Wisconsin). Just as significant is the fracturing of Biden’s 2020 electoral coalition that the polling suggests. Three years ago, black Americans backed Biden by a whopping margin of 78 percent: today, that margin is only 49 percent. He is also bleeding considerable support from Arab Americans and those under thirty, with his approval rating dropping a full eleven points among Democrats in just the past month.

Biden’s unwavering support for Israel’s brutal bombardment of Gaza is not the only reason his numbers have taken a dive, but the recent plummeting of his approval rating — and other polling that shows strong public support for a cease-fire — suggests it has been a factor. And while his zealous stance is clearly born of conviction as well as political calculus, the latter has obviously played some role — as indicated by an emblematic comment from a member of Biden’s team, who remarked to NBC that while the president’s posture was clearly eliciting a political backlash, “imagine the backlash from many more places if we hadn’t forcefully sided with Israel.”

In every presidential election in living memory, Democrats have insisted that defeating the Republican nominee is a task so imperative that all other considerations must be set aside. If that belief is sincere, it is difficult to reconcile with the idea that Biden should stand for reelection in the wake of recent events. Over the past month, Biden’s handling of the Israel’s war on Gaza has been a moral disgrace. It has also been counterproductive to the cause of averting a second Trump term. And however one ultimately rates the domestic achievements of the Biden presidency, it has clearly put them in peril as well.

Whatever political calculations may have factored into Biden’s decision to offer unconditional support for Israel’s assault on Gaza, they were evidently wrong — and catastrophically so.