Tim Walz and JD Vance are meeting for their first and possibly only vice presidential debate Tuesday, in what could be the last debate for both campaigns to argue their case before the election.

The debate in New York hosted by CBS News gives Vance, a Republican freshman senator from Ohio, and Walz, a two-term Democratic governor of Minnesota, the chance to introduce themselves, make the case for their running mates, and go on the attack against the opposing ticket.

Tuesday’s matchup could have an outsized impact. Polls have shown Vice President Kamala Harris and former President Donald Trump locked in a close contest, giving added weight to anything that can sway voters on the margins, including the impression left by the vice presidential candidates. It also might be the last debate of the campaign, with the Harris and Trump teams failing to agree on another meeting.

The role of a presidential running mate is typically to serve as an attack dog for the person at the top of the ticket, arguing against the opposing presidential candidate and their proxy on stage. Both Vance and Walz have embraced that role.

Vance’s occasionally confrontational news interviews and appearances on the campaign trail have underscored why Trump picked him for the Republican ticket despite his past biting criticisms of the former president, including once suggesting Trump would be “America’s Hitler.”

Walz, meanwhile, catapulted onto Harris’ campaign by branding Trump and Republicans as “ just weird,” creating an attack line for Democrats seeking to argue Republicans are disconnected from the American people.

A new AP-NORC poll found that Walz is better liked than Vance, potentially giving the Republican an added challenge.

After a Harris-Trump debate in which Republicans complained about the ABC News moderators fact-checking Trump, Tuesday’s debate will not feature any corrections from the hosts. CBS News said the onus for pointing out misstatements will be on the candidates, with moderators “facilitating those opportunities.”

Trump, on Tuesday evening, said his advice to Vance was to “have a lot of fun” and praised his running mate as a “smart guy” and “a real warrior.”

As they’ve campaigned, both Walz and Vance have played up their roots in small towns in middle America, broadening the appeal of Harris and Trump, who hail from California and New York, respectively.

Walz, 60, frequently invokes his past job coaching a high school football team as he speaks about his campaign with Harris bringing “joy” back to politics and weds his critiques of the GOP to a message to Democrats that they need to “leave it all on the field.”

Walz, a Nebraska native, was a geography teacher before he was elected to Congress in 2006. He spent a dozen years there before he was elected governor in 2018, winning a second term four years later.

He also served 24 years in the Army National Guard before retiring in 2005. His exit and description of his service have drawn harsh criticism from Vance, who served in the Marine Corps, including in Iraq.

The 40-year-old Vance became nationally known in 2016 with the publication of his memoir, “Hillbilly Elegy,” which recounts his childhood in Ohio and his family’s roots in rural Kentucky. The book was cited frequently after Trump’s 2016 win as a window into working-class white voters who supported his campaign. Vance went to Yale Law School before working as a venture capitalist in Silicon Valley.

After the publication of his book, he was a prominent critic of Trump’s before he morphed into a staunch defender of the former president, especially on issues like trade, foreign policy and immigration.