Donald Trump vowed on Sunday to hire 10,000 border guards if elected US president, as he stepped up his attacks on Kamala Harris on immigration. At a campaign rally in Arizona, the Republican presidential candidate also said he would ask Congress to fund a 10 percent pay increase for border patrol agents.

Flanked by Border Patrol unionists, who have voiced their support for Trump ahead of the Nov. 5 election, the former president said he would make sure the conditions are in place to “recruit and retain the border guards we need.”

Illegal immigration is one of the burning issues of the election campaign and, according to polls, Trump is seen by the majority of voters as the best person to deal with it.

Trump earlier this year opposed a bipartisan border security bill that would have provided funding to hire 1,500 border guards and customs officers, as well as an additional 1,600 workers in agencies that process asylum cases.

Currently, there are only 20,000 border guards in the US.

US Vice President Kamala Harris, the Democratic nominee in the Nov. 5 election, as well as President Joe Biden criticized Trump for his role in keeping Republicans from passing the bill, accusing him of sabotaging it for political gain.

About 7 million illegal immigrants have been apprehended trying to cross the US-Mexico border during Biden’s tenure in the White House, according to government figures.

Harris promised that her platform includes measures to fix the troubled immigration system, accusing Trump of fueling the “fire of fear and division” with his claims about the impact of immigrants on everyday Americans. He also advocated tighter restrictions on asylum and promised to make tackling the illegal entry of fentanyl (a synthetic opioid that has caused thousands of deaths) into the country a “top priority”.

On Friday, Trump called for the death penalty for “any illegal immigrant” who kills an American citizen. In recent weeks, he has stepped up his anti-immigrant rhetoric. Last month, referring to immigrants who commit violent crimes in the US, he referred to them as “monsters”, “cold-blooded killers” and “beasts”.

Studies have shown there is no evidence to support the claim that undocumented immigrants commit crimes at a higher rate than US residents, and Trump’s critics say the Republican mogul’s rhetoric fuels xenophobia.