Vice-presidential candidates Tim Walz and JD Vance sparred on stage during their one and only debate of the 2024 US election campaign.

Walz, the Democratic governor of Minnesota, and Vance, a Republican senator representing Ohio, traded claims on key election issues including immigration, foreign policy and reproductive rights.

Here are some claims from each candidate which the BBC Verify team fact-checked.

CLAIM: Vance: “We’ve got 20-25 million illegal aliens who are here in the country.”

VERDICT: These numbers are much higher than estimates for the number of illegal immigrants in the US.

Vance made this claim while criticising the border policies of President Joe Biden and Kamala Harris.

It is impossible to know exactly how many illegal immigrants have come to the US, as many will have evaded law enforcement agencies, but several estimates put the number at around half what Vance claims.

A report published by the Office of Homeland Security earlier this year estimated the number of illegal immigrants living in the US, as of January 2022, at 11 million.

Pew Research Center and the Migration Policy Institute came up with similar estimates for 2022 and 2021.

And the Center for Immigration Studies estimated there were approximately 12 million illegal immigrants in May 2023.

CLAIM: Walz: “Their Project 2025 is going to have a registry of pregnancies.”

VERDICT: This is false – Project 2025 does not mention a registry of pregnancies. There is no evidence that Donald Trump is planning to introduce one.

Here, Walz was trying to link Vance and Trump to Project 2025 – a wish list of ultra-conservative policy proposals by the Heritage Foundation think tank.

Walz might be referring to a section in the document which states that a future Trump administration “should use every available tool, including the cutting of funds, to ensure that every state reports exactly how many abortions take place within its borders”.

Project 2025 suggests that US health authorities and states should collect such data, but it does not refer to any new federal agency to register pregnancies.

Trump has repeatedly distanced himself from Project 2025 – though dozens of former Trump administration officials have contributed to the think tank’s proposals.

CLAIM: Vance: “Iran has received over $100bn in unfrozen assets by the Harris administration.”

VERDICT: This is false. There is no evidence that the Biden-Harris administration has unfrozen over $100bn (£75bn).

Speaking just hours after Iran launched a ballistic missile attack against Israel, Vance criticised the government over Iran.

Iran has had billions of dollars frozen in foreign banks as a result of international sanctions. Around $50bn of “useable assets” were unfrozen as part of the Iran nuclear deal negotiated under President Barack Obama in July 2015.

But Kamala Harris was not part of his administration.

There have been two agreements between the US and Iran under the Biden administration which released around $16bn in Iranian assets.

One was an extension of a deal introduced by Trump in 2018 which allowed Iran to access $10bn of frozen assets.

The other was a deal between the US and Iran made in September 2023, in which prisoners were exchanged and $6bn of Iranian assets released.

The deal stated that the unfrozen funds could only be used by Iran for humanitarian purposes.

BBC Verify has asked the Trump-Vance campaign what the basis for their $100bn claim is.

CLAIM: Walz said: “Donald Trump hasn’t paid any federal tax in the last 15 years”. He then added “in the last year as president”.

VERDICT: The first part of this claim – which was also posted on Walz’s X account during the debate – is false. The second part is true.

Trump has paid tax in the last 15 years but he did not pay any in the last year of his presidency.

A 2022 report, by the House Ways and Means Committee, released Trump’s federal income tax returns for the years 2015 to 2020.

They show he paid:

• In 2015, $641,931
• In 2016, $750
• In 2017, $750
• In 2018, $999,466
• In 2019, $133,445

However, in 2020, his last year as president, Trump did not pay any federal income tax – so Walz was right on this one year.

CLAIM: Vance: “We’re the cleanest economy in the entire world.”

VERDICT: This is false, according to two global rankings for overall environmental performance.

In 2024, the US was ranked 34th in the world overall by the Environmental Performance Index (EPI). It was 27th in the world for air quality, and 9th for water sanitation.

On one measure, minimising the threats of agriculture to the environment, the US came first.

Another monitoring body, the Climate Change Performance Index (CCPI) ranked the US 57th out of 63 countries and the European Union, in 2024.

CLAIM: Walz: “He promised… ‘I’ll build you a big, beautiful wall’… less than 2% of that wall got built.”

VERDICT: Even by the most conservative estimate of how much border wall was built under Trump, this figure is exaggerated.

We asked the Walz campaign about his claim and they pointed us to a report that 52 miles of “new primary wall” were built under the former president.

The US-Mexico border is almost 2,000 miles – 52 miles of wall would cover roughly 2.7% of it.

However, the length of border wall built during Trump’s presidency depends on what you are measuring.

A ‘Border Wall Status’ report in January 2021 found that – under Trump – 52 miles of “new primary wall” were built along with 33 miles of “new secondary wall”.

It said that if sections in which existing barriers were replaced or reinforced were included, he built 458 miles.

President Biden suspended construction of the wall when he came into office, but last year he approved the building of 20 miles of barriers along the border in southern Texas.

Reporting by Merlyn Thomas, Lucy Gilder & Jake Horton

North America correspondent Anthony Zurcher makes sense of the race for the White House in his weekly US Election Unspun newsletter.

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