While the Biden administration is handling the growing conflict as a highly sensitive diplomatic challenge involving a longstanding ally, the ascendant left views it as a searing racial justice issue that is deeply intertwined with the politics of the United States. For those activists, Palestinian rights and the decades-long conflict over land in the Middle East are linked to causes like police brutality and conditions for migrants at the U.S.-Mexico border. Party activists who fight for racial justice now post messages against the “colonization of Palestine” with the hashtag #PalestinianLivesMatter... On Thursday, a group of leading progressive members of Congress offered a rare break from party unity, giving fiery speeches on the House floor that accused Mr. Biden of ignoring the plight of Palestinians and “taking the side of the occupation.” Representative Alexandria Ocasio-Cortez of New York directly challenged the president, who had asserted that Israel had a right to defend itself. “Do Palestinians have a right to survive?” she asked in an impassioned address. “Do we believe that? And if so, we have a responsibility to that as well.”