Ohio Sen. JD Vance (R) is headed into the biggest test of his political career so far with next week’s vice-presidential debate against Minnesota Gov. Tim Walz (D). 

The first-term senator, looked at as a possible standard-bearer for the future of the MAGA movement, heads to the debate stage amid poor favorability numbers and ongoing scrutiny over his controversial statements and stances. 

The stakes are high for both rival running mates, who will have to make the case for their campaigns while pitching themselves to the debate’s national audience. But for Vance in particular, the showdown could be a make-or-break moment as he positions himself to be “the heir apparent” to Trump, said Tammy Vigil, a Boston University professor of media science with a focus on political campaigns. 

“Vance has been in the news so much, for a lot of not-always-positive things,” Vigil said. “He has an opportunity here to either try to change the narrative or reinforce the narrative.” 

Vance, a Marine veteran and former venture capitalist, entered the political scene with the success of his memoir, “Hillbilly Elegy,” which explored his upbringing around poverty and addiction in Appalachia. He was once a vocal critic of the former president but, when he lodged a Senate bid in the midterms, he defeated Rep. Tim Ryan (D-Ohio) with Trump’s endorsement. 

Vance has since become one of the most prominent faces of the America First movement in Congress. He has said he was “wrong” about Trump, and the former president has brushed off the past criticisms and touted the Ohio senator’s loyalty.  

Trump can only serve one more term and has said he won’t run again if he loses this year, making Vance a likely frontrunner for a potential run in 2028. 

Still, when Trump named him as his running mate, Vance was met with doubt from some in his own party, who raised concerns about his foreign policy positions and lack of political experience. 

Now, with a little over a month until Election Day, the polls look problematic for the VP contender. 

Vance and Trump are both underwater with their net favorability, or their favorable rating minus their unfavorable rating, according to aggregates from The Hill/Decision Desk HQ. 

Walz has a plus-4 net favorability score, with 44 perce

Walz has a plus-4 net favorability score, with 44 percent viewing him well. Voters are split on Harris, who has 49 percent favorability and a plus-1 net score. 

The former president has a net favorability at negative-10.5, with 54 percent saying they view him poorly. Vance’s net score is negative-11, with 49 percent viewing him unfavorably.

“Vance, at least if you look at the polls, is one of the singularly most unpopular vice presidential candidates around,” said Leonard Steinhorn, a professor of public communication at American University. 

Whether the first-term senator is able to improve those numbers in Tuesday’s debate “will depend on A) his demeanor, and B) how well he makes his case, how well he sort of sands the edges of some of the things that he’s been saying,” Steinhorn said. 

Vance has drawn backlash for a number of his remarks and stances, from his past critiques of Trump to comments calling out Democrats without children. He came under recent fire for amplifying a false claim about Haitian migrants and took a jab from pop superstar Taylor Swift for his past comments that the country was being run by “childless cat ladies,” which he has defended as a sarcastic comment. 

Across the aisle, Walz will take the stage facing his own hurdles. The Minnesota governor was relatively unknown outside of his home state when he went viral this summer for his folksy critiques of the “weird” Trump-Vance ticket, and still has to introduce himself to the national arena. He and Harris have both faced scrutiny for their progressive records as the campaign targets the center, and he’s been hit with criticism from the right over how he’s represented parts of his background, including his military record. 

But Vance is “more defined, and unfavorably,” than his Democratic rival, “so he needs to turn that around,” said Democratic strategist Steven Maviglio.

“I think [for] Walz there’s less pressure, because he just simply needs to define himself and not let Vance define him, so that’s the balance there.”

Republican strategist Mark Weaver, on the other hand, argued the debate could heap new scrutiny on Walz and showcase Vance’s media-friendly style. 

At the same time, Weaver said Vance would be smart to avoid wading into matters like Walz’s family fertility struggles, which could be “too personal a topic to bring up.” 

Vance’s main job is to perform better against Walz than Trump did against Harris on the debate stage in early September, when the vice president emerged as the ostensible winner, said Aaron Kall, the director of debate at the University of Michigan.

“In addition to some of Vance’s controversial comments on the trail or in interviews … Vance may have to clean up some of Trump’s comments from the debate,” Kall said, adding that may mean there’s “a little more pressure” on the Ohio senator.

But Kall also pointed out that Vance is “pretty good at interviews,” noting his regular appearances on the Sunday show circuit, which could bode well as the two men audition for the second-in-command job.

Vance will likely be “rather combative,” said GOP strategist Ron Bonjean, while Walz will likely come across as “more folksy” even as he responds to any attacks. 

“It’s just a chemistry we haven’t seen before with these two politicians on stage, and how it’s going to work between the two of them is anyone’s guess,” Bonjean said. 

Questions circulate every cycle about how much running mates matter to a White House bid. This year, Trump and Harris are both widely-known party figures, raising doubts that either Vance or Walz could change the game. Vice presidential debates are also typically seen as an undercard to the presidential showdowns, and experts are skeptical this year could buck historical trends and make major waves. 

But it’s an unprecedented election year, and the polls show Trump and Harris neck-and-neck in key battlegrounds. The latest national averages from DDHQ and The Hill have Harris ahead by 4 points nationally.

The tight polls and unique circumstances of Harris’s fast-tracked bid make it possible that even a slight impact could help tip the scales, experts say, adding potentially higher-than-usual stakes to the VP face-off. The Vance-Walz debate could also mark a closing argument for both campaigns, as a second presidential debate looks unlikely.

“There is so much that’s unique about this particular campaign and season altogether, and all the characters that are involved. And so I think that there really is an interest in getting to know the vice-presidential candidates a little bit more, because they haven’t been as front-and-center in years past,” said Vigil.

And if Vance is looking long-term, with the aim of inheriting Trump’s base, this debate could be key to creating “a bigger picture for himself,” Vigil said. 

The debate is set for 9 p.m. Eastern Tuesday night on CBS News, to be moderated by the network’s Norah O’Donnell and Margaret Brennan in New York City.