Trump made his pledge during a rally in Prescott Valley, Arizona, roughly 260 miles north of the state’s border with Mexico. He accepted an endorsement from the agents’ union, the National Border Patrol Council, which is a longtime Trump backer that endorsed him during his prior two campaigns.

Trump has made illegal immigration the focus of his campaign and blamed Vice President Kamala Harris, his Democratic opponent, for a record spike in unauthorized crossings at the U.S.-Mexico border. He frequently denounces people entering the U.S. illegally as invaders and criminals, and he has vowed to stage the largest deportation operation in American history if he is elected president again.

He did defy the union earlier this year when he convinced Republicans to kill a bipartisan immigration bill that contained additional border resources. According to the White House, the bill would have funded 1,500 personnel at U.S. Customs and Border Protection, which includes the Border Patrol.

Trump at the time said he did not want to give Democrats a political victory on his key issue. At the rally, Trump contended the legislation was “a horrible bill.”

Trump and his allies routinely call Harris the “border czar,” even though she’s never had that title. President Joe Biden did ask Harris early in his administration to study the “root causes” of migration from Central America.

“If we allow Border Czar Harris to win this election, every city, every community in this great country is going to go to hell,” union president Paul Perez said as he stood next to Trump on stage with a group of agents.

Matt Corridoni, a spokesperson for the Harris campaign, noted Trump’s move against the border bill and his vows that Mexico would pay for his signature border wall, which ultimately was funded by the U.S. government.

“Trump doesn’t care about solving problems, he only wants to run on one,” Corridoni said in a statement.

Trump has vowed to complete a border wall if he’s returned to the White House. He routinely trumpets his comparatively low numbers of border crossings with the much higher ones during Biden’s first three years in office, though currently crossings are back down to levels at or below those seen during most of Trump’s term.

Trump’s term was also marked by a struggle to crack down on illegal crossings before the COVID-19 pandemic led to international border closures. Under his administration, Border Patrol agents separated immigrant children from their parents, one of several enforcement programs the Trump administration implemented to target illegal immigration.

On Sunday, Trump said that Border Patrol agents deserved the higher pay and bonuses and bemoaned how he said Biden and Harris had neglected the border.