Many voters know little about Ohio Sen. JD Vance and Minnesota Gov. Tim Walz, the men selected to be one heartbeat away from the presidency. That’s not uncommon for vice presidential candidates, who rarely have a major effect on the outcome of races for the White House.

But the tightness of the 2024 election, potentially coming down to a small number of votes in a handful of battleground states, means extra scrutiny is being paid to Walz’s and Vance’s first and only debate, scheduled for Tuesday. Given former President Trump’s refusal to debate Vice President Kamala Harris again, the clash between their running mates — in front of the largest audience since they were chosen — could be the last time many voters hear directly from candidates on the GOP and Democratic tickets.

The race will come down to which party can drive more of its voters to the ballot box, with marginal swings potentially having an outsize effect, said Elaine C. Kamarck, senior fellow at the center-left Brookings Institution.

“This race is incredibly close in some of the swing states,” she said. “The problem with these kinds of races is when they’re so close, everything matters and nothing matters.”

The vice presidential candidates must litigate their respective standard-bearers’ arguments on issues such as reproductive rights, the economy and immigration, while raising their own public personas. But their No. 1 priority mirrors every physician’s imperative: “First, do no harm.”

Roughly one-quarter of Americans say they have not heard of Vance and Walz, the Pew Research Center found, just days before the two are scheduled to confront each other in the debate being hosted by CBS at the network’s broadcast center in New York City.

The Republican senator and Democratic governor were chosen, in part, to deliver a dollop of Midwestern earnestness — and hopefully a few votes — from a region of the country that has often been crucial in determining the winner of the presidential race.

Although both come from humble roots and are veterans, in many other ways their paths sharply diverged. Walz became a high school social studies teacher and a coach on the school’s football team. Vance attended Yale Law School, became a venture capitalist and wrote the best-selling “Hillbilly Elegy: A Memoir of a Family and Culture in Crisis.”

Minnesota Gov. Tim Walz delivers his 2021 State of the State address from the high school classroom where he once taught in Mankato, Minn.

(Glen Stubbe / Associated Press)

A challenge for the candidates will be conveying the lessons of their modest beginnings in a way that feels authentic, given how far they have advanced in the establishment.

“Captured by the bicoastal media, [Walz is] perceived … as kind of a rube,” said Karen Hult, a political science professor at Virginia Tech.

“I think he overstates his ‘aw shucks’ kind of manner. I expect to do a fair amount of cringing while watching,” the former Midwesterner said, before adding: “I think that kind of demeanor is a nice counterpoint to Sen. Vance, who will be very articulate. It will be interesting to see the extent [Vance focuses] on his alleged Appalachian background versus all the other things he has accomplished in his quite impressive life.”

Kamarck added that the impression on the screen may be “an angry scowling guy versus your son’s football coach at a backyard barbecue,” before adding that Vance probably will be a skilled debater.

“Vance is very smart, intellectually smart. He can throw a lot of things at Walz trying to paint him as a left-wing Marxist,” she said. “I think Walz has to be very careful to be able to answer those things and not come off as someone being too far left.”

JD Vance at a rally in 2021 in Middletown, Ohio, where he announced he would run for U.S. Senate.

(Jeffrey Dean / Associated Press)

Polls show that more people approve of Walz than don’t, whereas Vance’s approval rating started out poor and has gotten marginally worse.

The polling aggregation website 538 showed that when Vance entered the race in July, 28.9% of those surveyed viewed him unfavorably, 3.3 percentage points higher than those who had a favorable impression. By last week, the share who viewed him unfavorably had grown to almost 46%, more than 11 percentage points higher than those with a positive view.

Walz’s standing started on the plus side — with 31.4% viewing him favorably, more than 9 points higher than the share with a negative opinion of him. He remained in positive territory this week, though by a much narrower 3.5 percentage points.

The Ohio Republican is now widely known for saying during his Senate campaign that the U.S. was being run by Democrats and “a bunch of childless cat ladies,” and for having recently defended his need to “create stories” about Haitian immigrants in Ohio eating family pets, even after those reports were debunked.

The “cat ladies” barb earned a spot in meme infamy this month when pop music megastar Taylor Swift endorsed Democratic presidential nominee Kamala Harris and signed her online endorsement “Childless Cat Lady.”

Vice presidential scholar Joel K. Goldstein said that the vast majority of voters have deep impressions of Trump and Harris that will drive their decisions, with relatively little attention paid to their running mates.

Supporters listen as Republican vice presidential nominee JD Vance speaks at a campaign event Wednesday in Traverse City, Mich.

(Paul Sancya / Associated Press)

“Still, I tend to think that Vance is hurting Trump,” Goldstein said. “That’s in part because of the unfavorability but also because there seems to be this pattern of saying things that are offensive or demonstrably untrue and then doubling down on them.”

The vice presidential nominees arrived on the national stage for strikingly different reasons.

Trump selected Vance, now 40, in July, when Republicans still anticipated facing President Biden in the fall. Rather than pick a moderate to ideologically balance the ticket, Trump opted for a running mate who presented himself as a faithful adherent of the former president’s “America first” ideology.

“Trump likes to watch on TV and see people doing battle on his behalf,” said Justin Vaughn, a political scientist who has studied the presidency and vice presidency. “So I think that it was less about his need to have a MAGA heir, and more about this guy being exactly the kind of warrior he wants.”

Analysts view the 60-year-old Walz, in contrast, as a politician with a more moderate political profile, dating to his years in the U.S. House of Representatives, where he gained a reputation for his willingness to work with Republicans. Though he backed more liberal policies as governor — like providing free meals for all children in the public schools — his profile as a teacher and coach helped sustain his broader appeal.

“Walz is a successful messenger for Vice President Harris with a demographic that might not otherwise be her natural constituency — white working-class or middle-class voters who are rural or in small towns,” said Goldstein, who has written two books about the vice presidency. “As a high school teacher, National Guard member, football coach and gun owner, he might seem to have more in common with them.”

Tim Walz speaks to supporters at the Whitewater Music Hall Brewing Co. on Sept. 13 in Wausau, Wis.

(Morry Gash / Associated Press)

Although Trump held a wide 56%-to-42% advantage among white registered voters early in September, views among whites were much more positive for Walz, according to a survey by the Pew Research Center. Walz’s favorable rating was just 2 percentage points lower than his unfavorable rating in the Pew survey.

“He is one hell of an effective communicator and an extraordinarily likable person,” Kamarck said.

The trajectory of the two vice presidential campaigns has followed a familiar pattern: initial bursts of enthusiasm, followed by a more critical review of their past actions and statements.

More attention has been focused on Vance’s past statements, including his suggestion in a 2021 speech that parents should have more voting power than other citizens. “If you don’t have as much of an investment in the future of this country,” he said, “maybe you shouldn’t get nearly the same voice.”

During the campaign, Vance explained that his remarks on voting amounted to “a thought experiment” and not a serious policy proposal.

The Republican’s past statements shadowed him again Friday, when the Washington Post revealed a previously secret online communication: “Trump has just so thoroughly failed to deliver on his economic populism (excepting a disjointed China policy),” Vance wrote in February 2020.

The statement contradicted Vance’s public support of Trump and his previous claims that his skepticism about his current running mate faded after Trump’s strong performance in the White House. A spokesperson for Vance explained that, despite appearances, the previously private critique was actually aimed at “establishment Republicans who thwarted much of Trump’s populist economic agenda.”

Walz also has been forced to explain some of his past statements, particularly his claim — during a discussion of gun control to curtail school shootings — about “weapons of war, that I carried in war.”

Though he served in the National Guard for 24 years, Walz never deployed to a war zone. Pressed about his claim, the campaign released a statement saying that Walz “misspoke.”

On the stump this summer, the specter of Vance’s previous controversies has often faded, allowing him to prosecute a familiar complaint: that Democrats presided over an economy that pushed prices out of sight.

He told a rally in Raleigh, N.C., last week that eggs that once went for about $1.50 a dozen have jumped in price to “close to $4.” (Vance was lambasted for making the same claim at a Pennsylvania grocery story while standing in front of an egg display that showed a dozen priced at $2.99.)

The GOP vice presidential candidate also said in the Tar Heel State that the price of ground beef had jumped up to nearly $6 a pound, which he blamed on “Kamala Harris’ policies,” adding: “We just need to get back to commonsense economic policies so that American families can afford to feed their children the food that they want.”

Vance echoed Trump in blaming escalating prices in large part on higher fuel costs. The Republicans say they will bring prices down by expanding petroleum production. The Republicans’ cries of “Drill, baby, drill!” come as domestic oil production has already hit a record high under Biden.

Walz has also been rigorous in conveying the Democratic message. He argues, for instance, that the Republican promise of lower prices is mostly a mirage. “Gas prices go down under Donald Trump, “ Walz told a group of environmentalists in New York City recently, “because he botched the pandemic, and everybody’s stuck in their house and no one was driving.”

Supporters cheer and hold up signs as Tim Walz speaks at a campaign event on Sept. 12 in Grand Rapids, Mich.

(Al Goldis / Associated Press)

He returns frequently to the issue of abortion and how Trump’s elevation of three Supreme Court justices helped dismantle the federal right to abortion guaranteed under Roe vs. Wade. “It destroys women’s lives, it puts people at risk, and it’s hugely unpopular amongst the American public,” Walz said.

Walz also contrasts the two presidential candidates’ leadership styles, depicting Harris as “poised, thoughtful, compassionate [and] strong,” and Trump as “the guy yelling at clouds.”

Opinions on the presidential candidates are well-entrenched. Most of the 40 million or more estimated to watch Tuesday night’s debate will probably be viewing to cheer on their preferred candidate, said Aaron Kall, director of debate at the University of Michigan.

But given Trump’s refusal to agree to a second debate with Harris, the lone anticipated showdown by their No. 2s could loom larger. “The closer the election, the more important the debates can be,” said Kall, editor and co-author of “Debating the Donald.”

Among the experts certain that the veep choices won’t make a lot of difference: both members of the Republican ticket.

Trump assured Fox News anchor Harris Faulkner in late July that Vance “is outstanding in every way,” before adding: “But you’re not voting that way. You’re voting for the president.”

Vance soon followed his boss’ lead.

“My attitude is, it doesn’t really matter,” the would-be vice president said of his candidacy. “As much as this hits my ego.”