Vice presidential candidates Ohio Sen. JD Vance (R) and Minnesota Gov. Tim Walz (D) will face off in a debate Tuesday for the 2024 election cycle.

This will be the only time the candidates meet on stage and simultaneously present their policy positions to the broader American public, which may be less familiar with them than with their partners on the presidential ticket.

The two hold similar roles in their respective campaigns: to appeal to working-class voters in the “Blue Wall” states of Pennsylvania, Michigan and Wisconsin this fall.

Here’s what you need to know about what is historically the only debate between the candidates for vice president.

When and how to watch?

This debate will be hosted by CBS News in New York City at 9 p.m. ET.

CBS Evening News anchor and managing editor Norah O’Donnell and Face the Nation moderator and chief foreign affairs correspondent Margaret Brennan will moderate the debate at the CBS Broadcast Center. The debate will air live on CBS, CBS News Streaming Network and Paramount+ and stream live without a cable login on CBSNews.com.

Follow NPR’s live blog on Tuesday for the latest updates, analysis, fact-checking and color — and also watch the CBS News Vice Presidential Debate Simulcast. And you can listen to NPR’s special debate coverage on many public radio stations and in the NPR app.

Who are the running mates?

Former President Donald Trump announced Vance as his running mate on the first day of the Republican National Convention in Milwaukee this summer.

The first-term senator, who was once a critic of Trump, came to political relevance when he wrote the book Hillbilly Elegy, blaming Biden and Democrats for the struggles of the rural economy he grew up in. In the Senate, Vance has positioned himself against Republican leadership at times but on issues like abortion, immigration and election integrity, he’s closely aligned with Trump.

Vice President Harris chose Walz just weeks after she was tapped to replace President Biden at the top of the ticket.

Walz got the nickname “Coach Walz” for being a former football coach and teacher. As governor, Walz secured several progressive wins in his state, including clean energy mandates, universal free school meals, family and medical leave benefits and abortion protections.

What to watch for

Since his nomination, Vance has had to address controversies that are likely to come up again during the debate, including couch-related jokes and criticisms of him calling prominent Democrats “childless cat ladies.” Vance has also come under fire for spreading the false claim that Haitian immigrants are eating pets in Ohio.

Walz, a two-term governor, has also faced questions about his response to riots in Minneapolis following the 2020 murder of George Floyd and widespread fraud during COVID-19 under a federal program intended to provide food assistance to students after schools closed. Audits have suggested lapses in oversight by the state Department of Education.

Walz has been getting help for the debate from Pete Buttigieg, the U.S. Transportation Secretary. Buttigieg helped Harris with her VP debate prep in 2020. It wasn’t immediately clear whom Vance is preparing with.

The military records of both candidates are also likely to come up.

Vance criticized Walz for his military record, including for saying he carried weapons “in war” when he had not been in combat.

Walz, who served in the National Guard for 20 years and reenlisted after Sept. 11, only saw wartime deployment to Italy in 2003. Vance, who served in the Marines and did a six-month deployment to Iraq, also has not seen combat.

What are the rules for the debate?

The debate will last 90 minutes and both campaigns have agreed to a set of rules.

There will be no audience in attendance, and the candidates will each take a stand behind podiums. Candidates will have two minutes for closing statements. Vance won a virtual coin toss on Sept. 26 and elected to go second with his closing statement.

Vance and Walz will not be allowed to have prewritten notes or props, and topics and questions will not be shared in advance with campaigns. Unlike the presidential debates, microphones will remain on but CBS News reserves the right to turn them off.

According to CBS News, each candidate will get two minutes to answer each question, and the other candidate will get two minutes to respond. Then, each candidate gets one minute for further rebuttals. At the discretion of the moderators, candidates may get an additional minute each to continue a discussion.

What comes next?

This is likely to be the last debate before Election Day. Across several states, mail ballots have already started going out.

Harris challenged Trump to one more debate on Oct. 23 but Trump declined, saying it was “too late.”

Election Day is Nov. 5.