Sanders, like Mamdani, is a strident critic of how Israel has conducted the Gaza war. On Saturday, Mamdani appeared with Sanders on the senator’s national “Fighting Oligarchy” tour at a Brooklyn town hall, where Mamdani led the crowd in a rendition of “Happy Birthday” for the soon-to-be 84-year-old senator. Sanders spent time in Israel as a young man and has in past campaigns pushed back against anti-Israel invective from the left. Sanders ran for president in both 2016 and 2020, fueling hopes among supporters he could become the first Jewish president. On Saturday, Sanders called for “a foreign policy based on humanity,” drawing cheers of “Free Palestine” from the crowd.