Democrat Tim Walz and Republican JD Vance will face off tonight in the only scheduled U.S. vice presidential debate —a chance for each man to directly address the nation just five weeks before the Nov. 5 election.

Seven things to know About Vance, the 40-year-old running mate of Republican presidential nominee Donald Trump.

Meet the veep: JD Vance introduces himself as father, author - and MAGA convert

U.S. Marine veteran

Vance served in the Marine Corps and was a public affairs officer during a six-month stint in Iraq. He completed his undergraduate education at Ohio State using the G.I. Bill and went to Yale Law School with the help of student loans and side jobs.

Author of "Hillbilly Elegy," which became a Netflix film

The 2016 book outlined Vance's childhood and growing up in Ohio, amid a family struggling with addiction and poverty. It eventually became a bestseller and a film. Although its messaging around upward mobility and poverty has been criticized, it's also served as a pillar in Vance's connections to white, working-class voters.

First millennial vice president nominee

Vance has already made a name for himself as the first millennial vice presidential nominee. If Trump wins the White House, Vance will be the third-youngest vice president in history.

Tune into the CBS News Vice Presidential Debate on Tuesday, Oct. 1, at 9 p.m. ET on CBS or simulcast on www.usatoday.com.

In the past, he criticized Trump

Before becoming Trump's running mate, Vance was not a staunch Trump supporter, even calling him "America's Hitler" at one point. He has since backpedaled on his comments, saying he changed his mind about Trump, in an interview with Fox News.

He's a husband and a father

Vance met his wife and fellow attorney, Usha, while studying at Yale Law School. They have three children: Ewan, Vivek, and Mirabel.

"Some people tell me I’ve lived the American Dream, and, of course, they're right, and I'm so grateful for it," the Ohio senator said in his RNC speech. "But the American Dream that always counted most was not starting a business or becoming a senator or even being here with you fine people, although it's pretty awesome. My most important American Dream was becoming a good husband and a good dad."

Vance is a U.S. senator representing Ohio

Vance won his seat in the U.S. Senate in 2022 and won’t be up for re-election until 2028. If Trump wins the White House in November, Vance must resign before taking the oath of office as vice president on January 20, 2025.

He currently serves on the Joint Economic Committee, the Senate Committee on Banking, Housing and Urban Affairs, the Senate Committee on Commerce, Science, and Transportation, and the Senate Special Committee on Aging.

"I grew up in Middletown, Ohio, a small town where people spoke their minds, built with their hands, and loved their God, family, community, and country with their whole hearts," Vance said in his speech at the RNC. "But it was also a place that had been cast aside and forgotten by America’s ruling class in Washington."

At times, controversial

He has been criticized for referring to Harris and other Democrats in 2021 as a "bunch of childless cat ladies," and more recently, for spreading false claims that Haitian migrants in the Ohio city of Springfield were eating pets.

He has also claimed without evidence that the suspect in the latest assassination attempt against Trump was acting on Democrats' inflammatory language.