Seven Republican presidential candidates participated in a debate Wednesday night in California, while the front-runner in the party primary, former President Donald Trump, skipped the debate and instead gave a speech in Michigan amid a strike by autoworkers.

CNN is fact-checking both events. This article will be updated as additional fact checks are completed.

Christie vs. Pence on the border wall

Former New Jersey Gov. Chris Christie said that Trump "said he was going to build a wall across the whole border" but actually "built 52 miles of wall." Later in the debate, former Vice President Mike Pence used a much different figure, saying that "we built hundreds of miles of border wall."

Facts First: This needs context. Both candidates' claims are defensible; Christie, though, didn't explain that he was talking only about barriers that were erected in spots on the southern border where there had not been any barriers before. If you count all of the barriers built on the southern border under Trump, as Trump and Pence do, then the total is much higher -- more than 450 miles.

Here are the facts.

When Christie says only 52 miles of wall were built under Trump, he is referring solely to one category of wall construction -- "primary" wall that was built in parts of the border where no barriers previously existed.

When Pence puts the figure in the "hundreds of miles," he is referring to all wall construction during the Trump-Pence administration. The total number is 458 miles, according to a federal report obtained by CNN's Priscilla Alvarez: 52 miles of "primary" wall built where no barriers previously existed, plus 33 miles of "secondary" wall that was built in spots where no barriers previously existed, plus another 373 miles of primary and secondary wall that was built to replace previous barriers the federal government says had become "dilapidated and/or outdated."

While some Trump critics have scoffed at this replacement wall, the Trump-era construction was generally much more formidable than the older barriers it replaced, which were often designed to deter vehicles rather than people on foot. Washington Post reporter Nick Miroff tweeted in 2020: "As someone who has spent a lot of time lately in the shadow of the border wall, I need to puncture this notion that 'replacement' sections are 'not new.' There is really no comparison between vehicle barriers made from old rail ties and 30-foot bollards."

Ideally, Trump, Pence and their critics would all be clearer about what they are talking about: Trump and Pence that they are including replacement barriers, critics that they are excluding those barriers.

From CNN's Daniel Dale

Pence on immigration

Mike Pence, speaking of the Trump-Pence administration, claimed that "we reduced illegal immigration and asylum abuse by 90%."

Facts First: This is misleading. The total number of Border Patrol apprehensions, which is widely used as a proxy for illegal immigration, was actually higher during Trump and Pence's four years in office than it was in the final four years of the Obama administration, largely because of a major spike in early 2019. So where did Pence get the supposed 90% reduction? He didn't explain -- and didn't explain what he meant by "asylum abuse" -- but other fact-checkers, such as those at PolitiFact and The Washington Post, have found that you can find a roughly 90% drop in apprehensions if you compare the month with the highest Trump-era number of apprehensions, May 2019, to the month with the lowest Trump-era number, April 2020 -- in other words, by cherry-picking the most advantageous start and end dates.

The Trump-Pence re-election campaign did similar cherry-picking in a television ad in 2019, claiming Trump had cut illegal immigration in half. Small print in the ad made clear that the campaign, too, had started the clock in May 2019 rather than from the beginning of the administration.

CNN asked Pence's campaign two days before the September debate to explain the math behind this claim. The campaign did not respond.

From CNN's Daniel Dale

Trump's false claims Biden took money from foreign nations

During his speech, Trump accused President Joe Biden of "personally taking money from foreign nations, hand over fist. Look at the money he got from China. Look at what's coming out. China."

Facts First: There is no public evidence that Joe Biden himself made any money from foreign deals in China or elsewhere. That being said, Hunter Biden, the president's son, did earn millions of dollars from business deals in China, Ukraine, and other countries, including while his father was vice president, raising conflict-of-interest issues.

This has been one of the most persistent unproven claims from Trump and the congressional Republicans pushing for Joe Biden's impeachment.

Trump may have been reacting to new disclosures from House Republicans, who said Tuesday that they received documentation of wire transfers where Hunter Biden listed his father's address in Wilmington, Delaware, when receiving payments from Chinese nationals.

However, the files don't prove that Joe Biden received any money -- and Hunter Biden has lived at times at his father's home, and listed the address on his driver's license, according to previous CNN reporting.

From CNN's Marshall Cohen

Trump on Biden, Michigan and wheat

Trump scoffed at Biden's Tuesday visit to a United Auto Workers picket line in Michigan and claiming during his speech on Wednesday that Biden "had absolutely no idea what he was saying" and "didn't know where he was." Trump mockingly claimed that Biden said, "They grow wheat in Michigan." Trump then added, "That's Iowa."

Facts First: Trump's claim is false in two ways. Biden did not make any comments on Tuesday about Michigan growing wheat -- and Michigan actually does grow wheat, significantly more than Iowa. Iowa was a leader in wheat farming in the 19th century.

This is not the first time Trump has made a false claim about Biden while professing to be describing Biden's own confusion. In an interview on NBC earlier in September, he falsely claimed that Biden had claimed "he flew airplanes," though Biden did not.

From CNN's Daniel Dale