The CBS News Confirmed team is fact checking the biggest claims made by Minnesota Gov. Tim Walz and Ohio Sen. JD Vance in tonight's 2024 vice presidential debate in New York City.

CBS News is hosting the only planned vice presidential debate between Vance and Walz on Tuesday, Oct. 1, at 9 p.m. ET on CBS and CBS News 24/7. Download the free CBS News app for live coverage, post-debate analysis, comprehensive fact checks and more.

The debate moderators are "CBS Evening News" anchor and managing editor Norah O'Donnell and "Face the Nation" moderator and chief foreign affairs correspondent Margaret Brennan.

CBS News' live coverage of the vice presidential debate can be found here.

True: Walz claims former Trump White House chief of staff John Kelly called Trump "the most flawed human being he ever met."

Walz: "It's those that were closest to Donald Trump that understand how dangerous he is when the world is this dangerous. His chief of staff, John Kelly, said that he was the most flawed human being he ever met."

Details: John Kelly, a retired Marine general and former President Donald Trump's chief of staff, told those close to him in 2020 that Trump "is the most flawed person" he's ever known, according to CNN.

Kelly confirmed to CNN several stories that leaked out of the Trump administration during his presidency, among them, Trump's inflammatory comments about service members, calling them "losers" and "suckers." Kelly said, "A person that thinks those who defend their country in uniform, or are shot down or seriously wounded in combat, or spend years being tortured as POWs are all 'suckers' because 'there is nothing in it for them.'"

Trump denies making the comments.

By James LaPorta

Partially true: Walz claims "the last 12 months saw the largest decrease in opioid deaths in our nation's history — 30% decrease in Ohio."

Walz: "This is a crisis is — the opioid crisis. And the good news on this is the last 12 months saw the largest decrease in opioid deaths in our nation's history. 30% decrease in Ohio.

Details: Opioid deaths have fallen to the lowest levels in three years, provisional Centers for Disease Control and Prevention figures suggest, marking the first major decrease on record since deaths first began being tallied this way in 2015.

The CDC estimates that 77,461 deaths linked to opioids like heroin and fentanyl occurred in the year ending March 2024, down 7% from a year before nationwide.

The agency estimates 3,462 opioid deaths occurred in March 2024 — and for just Ohio, down 18% from March 2023.

By Alexander Tin

False: Vance says Vice President Harris "became the appointed border czar"

Details: Vice President Kamala Harris was not asked to be the administration's "border czar" or to oversee immigration policy and enforcement at the U.S.-Mexico border. That has mainly been the responsibility of Homeland Security Secretary Alejandro Mayorkas and his department, which oversees the country's main three immigration agencies, including Customs and Border Protection.

President Biden tasked Harris with leading the administration's diplomatic campaign to address the "root causes" of migration from Guatemala, Honduras and El Salvador, including poverty, corruption and violence. The region, known as Central America's Northern Triangle, has been one of the main sources of migration to the U.S.-Mexico border over the past decade.

In reality, the only role close to that of a "border czar" under the Biden administration was held for only a few months by Roberta Jacobson, a longtime diplomat who served as coordinator for the Southwest border until April 2021.

By Camilo Montoya-Galvez

Partially true, needs context: Vance claims housing unaffordable because "millions of illegal immigrants ... compete with Americans for scarce homes."

Vance: "You've got housing that is totally unaffordable, because we have brought in millions of illegal immigrants to compete with Americans for scarce homes."

Details: Research indicates that a growth in immigration under the Biden administration is one factor fueling housing demand. However, the housing shortage in the U.S. of an estimated 1.5 million to 7 million housing units has been a longstanding issue since the Great Recession, when the number of homes being built plummeted. Fewer new homes were built in the 10 years ending in 2018 than in any decade since the 1960s, according to Fannie Mae and Freddie Mac.

By Laura Doan and Emma Li

Mostly true: Walz claims when Iranian missiles "did fall near U.S. troops and they received traumatic brain injuries, Donald Trump wrote it off as 'headaches'"

Walz: "And when Iranian missiles did fall near U.S. troops, and they received traumatic brain injuries, Donald Trump wrote it off as headaches."

Details: Iran carried out a missile strike on Iraq's al-Asad air base on Jan. 8, 2020, days after the Trump administration ordered a lethal drone strike on IRGC commander Qassem Soleimani on Jan. 3, 2020, near Baghdad International Airport.

On Jan.17, U.S. Central Command said 11 service members were transported out of al-Asad after being screened for traumatic brain injury. Then-President Trump at first said there were no injuries related to the strike, then later referred to "headaches and a couple other things" that were later confirmed by the Pentagon to be incidents of traumatic brain injury. In the same remarks, on Jan. 22, 2020, he said he didn't consider the injuries to be "serious."

The Centers for Disease Control and Prevention says TBI is "a major cause of death and disability."

By Olivia Gazis

False: Walz claimed he was in China during the Tiananmen Square protests

Walz: "All I said on this was, I got there that summer and misspoke on this. That is what I have said. So, I was in Hong Kong and China during the democracy protests, went in and from that I learned a lot of what needed to be in governance."

Details: In 2014, then-Rep. Walz said he was in mainland China during the Tiananmen Square protests between April and June 1989 during a congressional hearing to mark 25 years since the massacre. According to a congressional transcript, Walz said, "As the events were unfolding, several of us went in. I still remember the train station in Hong Kong."

Minnesota Public Radio first reported Walz's exaggerated claims. A Chadron Record news report from April 1989 shows Walz would be leaving for China in August 1989. An Alliance Times-Herald news report from May 1989 shows then-Staff Sgt. Walz toured a Nebraska Army National Guard armory. The local news radio station also reported that in another Nebraska newspaper in August 1989, Walz said he would "leave Sunday en route to China."

As Minnesota governor, Walz has made several educational trips to China dating back to the late 1980s. In 2016, Walz claimed to have traveled to China "about 30 times" but his campaign admitted to Minnesota Public Radio it was "closer to 15."

By James LaPorta

True: Walz claims Vance has in the past said "there's a climate problem" and that Trump called climate change "a hoax"

Walz: "Sen. Vance said there's a climate problem in the past. Donald Trump called it a hoax and then joked that these things would make more beachfront property to be able to invest in."

Details: Former President Donald Trump has described global warming or climate change as a "hoax" on multiple occasions. "The global warming hoax, it just never ends," Trump said during a March 2022 speech in New Orleans, the Washington Post reported. "To which I say, great, we have more waterfront property."

Prior to his election to the Senate, Vance said in a 2020 speech at Ohio State University, "We, of course, have a climate problem in our society."

By Steve Reilly

Partially true: Walz claims patients had to pay $800 for insulin before passage of Inflation Reduction Act during Biden administration

Walz: "The $35 insulin is a good thing, but it costs $5 to make insulin. They were charging $800 to make it before that law went into effect."

Details: A handful of researchers have tried to estimate the cost of different insulin medicines, coming up with production costs that often work out to single-digit costs for the monthly supplies of drug.

One published in January touted by Medecins Sans Frontieres estimated reusable pens of insulin could be competitively manufactured for as little as $96 a year – or $8 per month.

The Biden administration said the list price for a 30-day supply of Novo Nordisk's insulin pen products, that it targeted for its Medicare Drug Price Negotiation Program, was $495 for a 30-day supply in prices set for 2023.

However, those list prices do not reflect myriad confidential markups and rebates that muddy the actual price that individual insurers and patients pay.

By Alexander Tin

Needs context: Walz claims Project 2025 makes it hard to get contraception and access to fertility treatments

Walz: "Their Project 2025 is going to have a registry of pregnancies. It's going to make it more difficult, if not impossible, to get contraception, and limit access, if not eliminate access, to infertility treatments."

Details: Project 2025 does not call for a registry of pregnancies.

However, it does call on state reporting of "how many abortions take place within its borders, at what gestational age of the child, for what reason, the mother's state of residence, and by what method." Project 2025 also calls on the Health and Human Services to use "every available tool, including the cutting of funds" to ensure this state reporting is conducted.

There would be measures included in the Project's policies that could make it more difficult to access contraception.

Project 2025 calls for the restoration of "Trump religious and moral exemptions to the contraceptive mandate." These exemptions allowed for "religious and moral exemptions and accommodations for coverage of certain preventive services under the ACA."

By Jui Sarwate and John Kelly

This article will be updated with additional fact checks as the debate continues.