As Democrats weathered the upheaval caused by Joe Biden’s decision to end his re-election campaign and hand the reins to his vice-president, Kamala Harris, a party stalwart piped up with a suggestion: start calling Donald Trump “weird”.The pioneer of the attack, which was also deployed by Harris’s campaign, was Minnesota governor Tim Walz, who insisted to CNN that “it’s not a name-calling or tagging him with it. It’s an observation.”“And I didn’t come up with it,” he added, noting that he had heard “relatives and Republicans” use the adjective to describe the former president.Walz is now expected to spend the next three months telling the country all about the weirdness of Trump and his running mate, Ohio senator JD Vance, after Harris named the Minnesota governor as her pick for vice-president on Tuesday. Although the 60-year-old is one of the least nationally known of the options Harris was considering, and does not hail from a state viewed as crucial to deciding the election, he is expected to assist Harris in making the case for her policies, and convincing voters to reject the extreme remaking of the US government that Trump says is required.Now in his second term as governor, the former congressman and high school teacher brings to the ticket a record of progressive policymaking, a somewhat sympathetic view towards pro-Palestine protesters, and a distinctly Minnesotan style of communication the campaign could use in its efforts to win the nearby swing states of Wisconsin, Michigan and Pennsylvania.“If Donald Trump and JD Vance are irritated that Kamala Harris smiles and laughs, they’re really going to be irritated by Tim Walz,” Melissa Hortman, the Democratic speaker of Minnesota’s house of representatives, told the Guardian.“He is a cheerful person, he’s a positive, upbeat person, he’s charismatic. He can get a crowd going.”Walz emerged as Harris’s pick after a search lasting two weeks that saw the vice-president also consider a group that included Pennsylvania governor Josh Shapiro and Arizona senator Mark Kelly. The choice of Walz drew praise from across the Democratic party’s ideological spectrum.Progressive congresswoman Alexandria Ocasio-Cortez said Harris made an “excellent decision”, while Joe Manchin, the West Virginia senator who recently left the party and is best known for hamstringing Biden’s proposals to fight child poverty and more aggressively combat climate change, said: “I can think of no one better than governor Walz to help bring our country closer together and bring balance back to the Democratic party.”Republicans responded to Walz’s selection by posting on social media images of the protests the rocked Minneapolis four years ago after George Floyd’s murder, reminders of the governor’s support for a law allowing undocumented migrants to obtain driver’s licenses, plus a massive Covid relief scandal that took place during his administration.With Trump making fears of crime and unrest a centerpiece of his platform, Amy Koch, a Minnesota Republican strategist and former state senate majority leader, said the unrest that followed Floyd’s killing will likely form a plank of the party’s counter-attack to Walz’s candidacy.“There’s a lot of video of five days of chaos in Minneapolis,” Koch told the Guardian. “There’s a lot of video of, like, literally, reporters covering it, saying: where is governor Walz?” The governor did deploy the national guard, but Republicans say he did not do so soon enough.Walz’s main competitor for the spot of running mate was Shapiro, who may have reignited tensions among Democrats over his policy positions on issues such as education, fracking and Israel-Gaza.Biden’s support for Benjamin Netanyahu and the invasion of Gaza sparked a backlash that some of his allies feared could have cost him victory in swing states such as Michigan, home to a large Arab-American population. Some pro-Palestine activists have signaled a willingness to give Harris a chance to win back their votes, but were wary of Shapiro, who took a hardline stance against pro-Palestinian protests.The backlash to his potential candidacy, which included the formation of a group called “No Genocide Josh”, itself attracted claims of antisemitism, with many pointing out that Shapiro, who is Jewish, has condemned Netanyahu and that Walz has a similar record of support for Israel and campus protests.Walz took a different rhetorical tack on other protests. When tens of thousands of Minnesotans voted “uncommitted” in the Democratic primary in protest against the Biden administration’s policies towards Gaza, his response was warm, with the governor calling them “civically engaged”.“They are asking to be heard and that’s what they should be doing,” Walz said at the time. “Their message is clear that they think this is an intolerable situation and that we can do more. And I think the president is hearing that.”After his selection, the pro-Palestine group IfNotNow said it remained “concerned” by Walz’s past association with the American Israel Public Affairs Committee (Aipac) and votes in Congress to approve military aid to the Israel.Supporters of Shapiro had argued that putting him on the ticket would help Harris win Pennsylvania, perhaps the most crucial swing state this election. But Christopher J Devine, a political science professor at the University of Dayton, said his research showed there was no guarantee of that happening.The choice of running mate was the last major piece of unfinished business before Harris, who quickly consolidated the support necessary to become the presumptive Democratic nominee after Biden withdrew last month.As hotly anticipated as Harris’s decision was, Devine said it was unlikely to prove decisive in beating Trump and Vance.“VPs can have an effect on the election. It’s not always in the way we expect, and the magnitude of that effect tends not to be very large,” said Devine, the author of Do Running Mates Matter? The Influence of Vice Presidential Candidates in Presidential Elections.If elected, Harris would be the first female president and the first south Asian president, and only the second African American, after Barack Obama. Her shortlist of running mates was composed entirely of white men after the Michigan governor Gretchen Whitmer said she was not interested in the job.While Devine said that may have been a calculation on Harris’s part – besides Obama, every US president has been a white man – he said it did not mean she had no choice but to select a running mate from that demographic.“Kamala Harris could have chosen Gretchen Whitmer if she believed that there was strength in that identity of being a woman running for the presidency,” he said. “But I suspect her calculation, or a lot of her team, they might have weighed on her to … say that it just can’t be done. It’s too much for people to handle.”Trump has made dissatisfaction with both the Biden administration and the country’s entire direction a theme of his campaign, going so far as to say that the country is being “destroyed”. William G Howell, director of the University of Chicago’s Center for Effective Government, said Walz will be put in a position to articulate the case against that worldview.“His is the language of us coming together and … setting to work on hard problems,” Howell said. “And so, both in tone and in substance, he’s going to be able to clearly distinguish himself from from the kind of rhetoric emanating from Trump.” More