Washington — Sen. JD Vance and Minnesota Gov. Tim Walz will face off on Tuesday in the first and only vice presidential debate of the cycle, as the two candidates look to prop up the Republican and Democratic tickets with fewer than 40 days until Election Day.

The debate, hosted by CBS News at the CBS Broadcast Center in New York City, will be moderated by "CBS Evening News" anchor and managing editor Norah O'Donnell and "Face the Nation" moderator and CBS News chief foreign affairs correspondent Margaret Brennan.

Here's what to know about how the candidates are preparing for the debate:

How JD Vance is preparing for the VP debate

The Ohio Republican has been preparing for the debate for more than a month, a source directly involved told CBS News, including with "murder board" sessions with a small team that includes Vance's wife and his advisers, along with senior Trump adviser Jason Miller.

Among Vance's main focuses during the preparation has been studying Walz' debate style and policy record, the source said, noting that Vance will attempt to highlight what he sees as the Minnesota governor's left-wing views during the debate.

Vance told reporters last week that his plan is to break down what the Trump-Vance administration would do to make "life better" and connect that to policy.

"So, we're studying up as much as we can on the issues that matter to the American people, and I'm looking forward to it," Vance said.

House Majority Whip Tom Emmer, a Minnesota Republican, is standing in for Walz during Vance's debate prep, four sources familiar with the preparations told CBS News. Emmer and Walz have deep roots in Minnesota and are close in age.

Emmer told ABC's "This Week" on Sunday that he's known Walz for decades and has spent the last month working to "get his phrases down, his mannerisms."

"My job was to be able to play Tim Walz so JD Vance knows what he's going to see," Emmer said.

How Tim Walz is preparing for the VP debate

Walz has been preparing for the debate with a close team of advisers, a source familiar with the preparations told CBS News. Some of the people involved also helped Vice President Kamala Harris take on former President Donald Trump, among others, like a long-time aid to Walz who worked with him during his bids for governor.

For Walz, whose name recognition was until recently limited outside of Minnesota, the focus is on continuing to introduce himself to the American people, according to the source. He'll also work to highlight Harris' vision for the nation's path forward.

"You'll hear me talk like I have about things that impact Americans, making sure they have the opportunity to thrive, making sure that we're being factual in how we talk about that," Walz told MSNBC's Rachel Maddow of the debate earlier this month. "And so I'm looking forward to it. I'll work hard, that's what I do."

During debate prep, Transportation Secretary Pete Buttigieg is standing in for Vance, a campaign official familiar with the preparation told CBS News. The former mayor of South Bend, Indiana, also assisted Harris during her debate prep in 2020, and is close in age to Vance.

When and how to watch the presidential debate

Debate coverage on CBS News 24/7 begins at 4 p.m. ET, with the debate getting underway at 9 p.m. ET on Oct. 1.

The 90-minute debate will be streamed on CBS News 24/7 and Paramount+ across all available platforms and CBSNews.com. The debate will also be simulcast across other broadcast and cable networks.

, , , , , , and contributed to this report.