Last year’s Democratic vice-presidential nominee has thrown himself into a robust atonement-and-explanation tour, though aides insist there is no grand strategy.Nearly seven months since his ticket lost the 2024 presidential election, Tim Walz is trying all at once to make amends for everything he thinks went wrong.He is going to Republican areas where Democrats lost ground. He is sitting for countless interviews after former Vice President Kamala Harris’s campaign limited his media exposure. And as his party engages in collective finger-pointing, he is among the few Democrats admitting that they themselves made mistakes.“I know my job and I didn’t get...