EXCLUSIVE: A deep-pocketed outside political committee that supports former President Trump's White House campaign is taking aim at Vice President Kamala Harris over the issue of border security.

"America needs a commander-in-chief who's tough on illegal immigration. Kamala Harris fails that test," National Border Patrol Council vice president Art Del Cueto charges in a new ad from the Preserve America super PAC.

The spot, shared first with Fox News Digital on Friday, is the latest by either the Trump campaign or aligned super PACs that target Harris for being weak on border security, which many Republicans see as the vice president's political Achilles' heel.

HARRIS LEANS IN ON BORDER SECURITY AND TRUMP RELISHES THE FIGHT

Trump and his allies have repeatedly criticized Harris for nearly two weeks — since she replaced President Biden at the top of the Democrats' national ticket — over the surge of migrants across the nation's southern border during the Biden administration.

Harris was tasked by Biden in 2021 with leading the diplomatic outreach to tackle the "root causes" of migration in Central American countries. It led to her being dubbed the "border czar" both by the media and Republican opponents, although the White House has rejected that description.

2024 AD WARS: TRUMP, HARRIS RACE TO DEFINE VICE PRESIDENT

Del Cueto — who has endorsed the former president and who joined Trump running mate Sen. J.D. Vance at a campaign event Thursday along the U.S.-Mexico border in Arizona — calls Harris "Biden's border czar" in the ad, which was filmed along the southern border.

Republican vice presidential candidate Sen. J.D. Vance, R-Ohio, addresses the media during his visit to the U.S.-Mexico border in Hereford, Arizona, on Thursday, Aug. 1, 2024. 

Republican vice presidential candidate Sen. J.D. Vance, R-Ohio, addresses the media during his visit to the U.S.-Mexico border in Hereford, Arizona, on Thursday, Aug. 1, 2024.  (Grace Trejo/Arizona Daily Star via AP)

"She supported sanctuary cities and taxpayer benefits for illegal immigrants. And she created the worst border crisis in American history. Kamala Harris is dangerous," he argued. 

The spot also includes a Harris interview on "The View" from August 2019 — when she was running unsucessfully for the 2020 Democratic presidential nomination — in which she said, "We are not going to treat people who are undocumented cross the border as criminals. That is correct."

The ad is the second straight one from Preserve America to criticize Harris over border security. The group tells Fox News that it is spending at least $10 million to run the spots from the Olympics through Labor Day as part of an ad blitz in the key battlegrounds of Michigan, Pennsylvania and Wisconsin.

Preserve America was set up during Trump's unsuccessful 2020 re-election bid and was re-launched this spring to help the former president try to win back the White House in 2024.

REPUBLICAN MEGA DONOR BANKROLLING TRUMP-ALIGNED GROUP

Multi-billionaire Miriam Adelson, the controlling shareholder of the Las Vegas Sands gambling empire, is helping to bankroll the super PAC's efforts, a source with knowledge of her plans confirmed to Fox News a couple of months ago.

Adelson and her late husband, casino magnate Sheldon Adelson, shelled out roughly $90 million to Preserve America four years ago. Sources indicated that the super PAC plans to increase its expenditures from what it spent in 2020 on behalf of Trump.

Harris has been pushing back on the border security attacks as she leans in on the issue.

Over 10,000 at a Kamala Harris rally in Atlanta, Georgia

Vice President Kamala Harris speaks during a campaign rally, Tuesday, July 30, 2024, in Atlanta. (AP Photo/John Bazemore) (AP Photo/John Bazemore)

"In this campaign, I will proudly put my record against his," Harris said at a rally in Atlanta on Tuesday before highlighting her border security efforts as California attorney general.

The vice president argued that Trump, the Republican presidential nominee, "has been talking a big game about securing our border, but he does not walk the walk."

She pointed to a border security bill with some bipartisan support that had been making its way through Congress earlier this year before Republicans turned against the measure after prompting from Trump.

"It was all set to pass, but at the last minute Trump directed his allies in the Senate to vote it down," Harris said. 

She charged that the former president "tanked the bipartisan deal because he thought it would help him win an election" and pledged that "as the president, I will bring back the border security bill that Donald Trump killed."

Harris migrants border

Vice President Kamala Harris and migrants at the southern border. ( (Photo by Drew Hallowell/Getty Images and Qian Weizhong/VCG via Getty Images))

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The Trump campaign quickly took to social media to respond to the comments by the vice president at her rally.

"Kamala is actually *BRAGGING* about her record on immigration. HERE ARE THE FACTS: As Border Czar, Kamala ferried 15+ million illegals directly into our communities. She thinks illegal immigration "is NOT a crime." She wants to abolish ICE. She thinks you're stupid," the Trump campaign claimed.

Hours earlier, the Trump campaign — in its first major ad blitz of the general election — charged that Harris had "failed us" in securing the border.

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.