Democrat Tim Walz and Republican JD Vance will face off next month in the only scheduled US vice presidential debate, a chance for each man to reinforce his running mate's message to voters just weeks before the November 5 election.

Here are some details about the event:

When and where is the debate?

The 90-minute debate, hosted by CBS News, will take place on October 1 at 9pm ET (0100GMT on October 2) in New York City, a Democratic stronghold that is the former home of Donald Trump, the Republican presidential candidate running against Democratic Vice President Kamala Harris.

Who are the moderators? 

The debate will take place at the CBS Broadcast Centre and be moderated by CBS "Evening News" anchor Norah O'Donnell and "Face the Nation" moderator Margaret Brennan.

How can you watch the debate?

The event will be broadcast on the CBS network and live streamed on all platforms where CBS News 24/7 and Paramount+ are available. CBS said it will also be made available to simulcast.

The September 10 presidential debate between Harris and Trump on ABC News drew 67 million television viewers.

What are the ground rules? 

The ground rules for the debate are not yet public. At the September presidential debate, the candidates' microphones were muted when it was not their turn to speak, and there was no studio audience.

What to expect from Walz?

Walz, the governor of Minnesota, will likely use his "regular guy" reputation to try to appeal to voters, including some independents, who view Harris, a former senator from California, as too liberal.

The 60-year-old Walz is a former congressman who won elections in a Republican-leaning district before becoming governor.

As governor, he has pushed a progressive agenda including free school meals, tax cuts for the middle class and expanded paid leave for Minnesota workers.

Walz will likely try to needle Vance, as Harris did successfully in her debate with Trump. Walz has questioned Vance's midwestern credentials and derided his 2016 memoir "Hillbilly Elegy" for its depiction of rural America.

"Like all regular people I grew up with in the heartland, JD studied at Yale, had his career funded by Silicon Valley billionaires and then wrote a bestseller trashing that community," Walz said at his first rally as Harris's vice presidential pick. "Come on! That's not what middle America is."

Walz, also a former high school teacher and football coach, has dismissed Trump and Vance as "creepy and, yes, weird," - a takedown that spread widely among Democrats.

The Democratic vice presidential candidate has linked Vance to a set of conservative policy proposals known as Project 2025, from which Trump has tried to distance himself.

What to expect from Vance?

Vance, a US senator from Ohio, will have to work hard not to be on the defensive throughout the debate if Walz employs Harris's debate strategy.

Vance, 40, likely will face questions about his inflammatory rhetoric and could punch back with his typical combative style.

He has been criticised 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.

"The big difference between conservatives and liberals is that ... no one has tried to kill Kamala Harris in the last couple of months and two people now have tried to kill Donald Trump in the last couple of months," said Vance in comments that drew a rebuke from the White House.

On the campaign trail, Vance has portrayed Walz and Harris as radical liberals.

He also has questioned Walz's depictions of his military record and his family's fertility struggles.

Vance, who served in the Marine Corps and was a public affairs officer during a six-month stint in Iraq, has accused Walz of leaving the Army National Guard to avoid getting deployed to Iraq and of falsely suggesting he served in combat.

Walz, who served in the Guard for 24 years, retired to run for Congress. He has defended his record, but the Harris campaign has acknowledged he misspoke in a 2018 video in which he referenced "weapons of war that I carried into war." Walz never served in a combat zone.