Sen. JD Vance refused to acknowledge that former president Donald Trump lost the 2020 election, setting off one of the most contentious exchanges in Tuesday night’s vice-presidential debate with Gov. Tim Walz. Walz vigorously pressed Vance on the issue near the end of a debate that had otherwise been marked by unusual comity. “I would just ask, did he lose the 2020 election?” Walz asked. “Tim, I’m focused on the future,” Vance said, without addressing the question. “That is a damning non-answer,” Walz responded. The Republican senator from Ohio and the Democratic governor of Minnesota offered sharply different perspectives on...