Republican vice presidential candidate JD Vance visited Arizona’s southern border on Thursday, accusing Vice President Kamala Harris, the likely Democratic presidential nominee, of fomenting chaos through lax border policies.

"It is unbelievable what we're letting happen at the southern border and we're letting it happen because Kamala Harris refuses to do her job," Vance said in a news conference.

Vance echoed misleading Republican attacks on Harris as Biden's "border czar," even though that wasn't her role. Harris was tasked with addressing the root causes of migration from Central America. 

The number of migrants crossing the southern border illegally surged after President Joe Biden took office and eventually reached record levels. But border crossing numbers have fallen to the lowest level in more than three years after Biden in June imposed new restrictions on people seeking asylum.

Vance on Thursday called for the resumption of the Trump-era "Remain in Mexico" policy and repeated a common Republican claim that the administration's border policies are to blame for America's deadly fentanyl crisis.

"Because of the poison that Kamala Harris has let come into this country, there are a lot of those prayers that won't be answered," Vance said. "There are a lot of parents that won't wake up because when you take fentanyl, you don't wake up."

Statistics indicate that it is rare for migrants illegally crossing the border to be smuggling the drug. According to U.S. Customs and Border Protection, more than 90% of fentanyl siezed by agency is trafficked in cars and trucks through legal ports of entry. And an analysis by the Cato Institute, published in 2023, found that fentanyl is "primarly tracked by U.S. citizens," noting that U.S. citizens accounted for 86.3% of fentanyl trafficking convictions. 

Vance also defended former President Donald Trump's false claim, made before a group of Black journalists Wednesday, that Harris started identifying as black in recent years for political expediency. Harris, he said, "happened to turn Black" a few years ago, after being "Indian all the way."

Harris, the daughter of immigrants from Jamaica and India, graduated from the historically Black university Howard University, was a member of Alpha Kappa Alpha, a historically Black sorority, and was a member of the Congressional Black Caucus during her tenure in the U.S. Senate.

"She presents to be somebody different, depending on which audience she's in front of," Vance said. "I think it's totally reasonable for the President to call that out."

On Wednesday, while in the Phoenix area, Vance told reporters that he thought Trump’s comments were "hysterical."

“So what he said, I thought it was hysterical. I think he pointed out the fundamental chameleon-like nature of Kamala Harris,” Vance said. 

Harris has called Trump's remarks about her racial identity the "same old show."

“And let me just say, the American people deserve better, the American people deserve better,” Harris said. “The American people deserve a leader who tells the truth, a leader who does not respond with hostility and anger when confronted with the facts.”

Trump will rally Saturday with Vance in Georgia, and Harris is expected to announce her VP pick by Tuesday and join her running mate in Pennsylvania on Tuesday to kick off a tour of several battleground states.