Vice President Kamala Harris’ vice-presidential pick Tim Walz is known for bonding with rural voters who other Democrats can’t reach.

That’s one big reason why the Minnesota governor, who is largely unknown to most Americans, now finds himself on a major party ticket in the most intense sprint to an election in modern history following President Joe Biden’s late decision to abandon his reelection bid.

The selection of Walz reveals the geographic and demographic key to the 2024 election. If Harris is to win, her path will most likely run through Pennsylvania, Michigan and Wisconsin, which Donald Trump captured in 2016 only to lose them to Biden in 2020. Presently, they are threatening to tilt back to the Republicans again this year.History suggests that vice presidential nominees rarely deliver a state to their ticket-mates as voters tend to focus on potential presidents. But Walz, a friendly and jocular leader whose urbanity doesn’t conceal an acidic partisan tongue, provides a political complement to Harris.

The vice president will hope to perform strongly among minority voters in cities like Detroit, Pittsburgh, Philadelphia and Milwaukee and to run up Democratic numbers among suburban and women voters alienated by Trump. Walz may be able to help most by reaching out to rural Americans wavering over a vote for the ex-president but who are not yet convinced by the new Democratic nominee or may find her too liberal.

One of the key developments in Midwestern politics in recent years has been the shift of some White, working class and male voters from Democrats to Republicans, including those who voted for President Barack Obama in 2008 and 2012 but who were won over by Trump’s cultural conservatism and populist, nationalist economic values in 2016. If Walz can winnow Trump’s margins outside the cities in these states even by a few thousand votes, he could make an important contribution to the Harris campaign in a knife-edge race.

The importance of the Midwestern trio of states is no secret. Trump also appeared to have this in mind with his choice of Ohio Sen. JD Vance as his running mate, whose political emergence epitomizes the transformation in the region’s politics.

Walz has emerged as something of a Democratic folk hero in recent days. In a party where many members appeared to be reconciled to defeat under Biden, he has added a carefree tone and coined a new angle of attack against Trump and Vance that delighted Democrats – branding them “weird.”

Harris’ decision to choose Walz, a 60-year-old former congressman, progressive, Army National Guard veteran and schoolteacher will be seen by some experts as a “safety first” move. The vice president certainly had a strong incentive to do nothing to upset her momentum after securing the Democratic nomination in a surreal period since Biden’s exit from the race just over two weeks ago.

And the perils of a botched vice-presidential rollout were illustrated in recent days as Trump and his team spent two weeks defending Vance after his past reference to Democratic politicians as “childless cat ladies” created the rockiest rollout of a vice-presidential pick since Republican Sarah Palin in 2008.

The question now is whether the compressed vetting period left any political skeletons or missteps the Trump campaign can discover and highlight.

Walz won the spot after Harris chose him over Pennsylvania Gov. Josh Shapiro, the other finalist in her hurried running mate search. The Keystone State governor offered the potential promise of helping to secure Pennsylvania’s 19 electoral votes.

But Shapiro, who is Jewish, was criticized by some on the left for comments condemning the tone of campus protests. While he has been more outspokenly critical about the choices made by Israeli Prime Minister Benjamin Netanyahu than the president, some progressives had warned against his selection as vice presidential nominee.

One potential line of attack against the vice president may be that she decided not to contradict the most liberal voices in her party who were strongly against Shapiro.

And there is some relief among Republicans that a Democratic governor who easily won Pennsylvania and has high approval ratings did not get the nod from Harris. But Shapiro, a Democratic rising star, is likely to remain a vocal advocate for the Democratic ticket in the commonwealth.

Walz and Harris will hold their first joint appearance at a rally in Philadelphia on Tuesday night that will kick off a sprint across an electoral map expanded Biden’s shelving of his campaign.

The theatrics will offer the vice president a fresh chance to supercharge her candidacy’s momentum, which has energized a party that had looked headed for defeat in November and tightened the contest into a 50-50 struggle in a polarized country. Her relative youth, at 59, has inverted the generational contrast with Trump, 78, now that the issue of Biden’s age and acuity in a potential second term is moot.

While the naming of the Democratic vice presidential pick is the focus of the campaign, new developments Monday – outside a race that has been on a momentous trajectory since Trump escaped an assassination attempt and Biden pulled out – hinted at potential new twists to come before November.