Since the war in Gaza began, the threat of a protest vote — in which voters would choose to abstain from the presidential election or vote for third-party candidates who had no shot of winning — hung over Democrats’ heads because of President Joe Biden’s unconditional support for Israel and its right-wing government. When Vice President Kamala Harris became the nominee, her lack of willingness to distance herself from Biden on this issue didn’t help alleviate that threat. Meanwhile, Donald...