U.S. President Joe Biden condemned violent threats against FBI agents who searched predecessor Donald Trump's home as "sickening," as he called for more police funding and an assault weapons ban in Pennsylvania.

Launching his first of three visits in a week to the political battleground, Biden angrily denounced people who have lashed out at federal law enforcement officials involved in the unprecedented search of the Republican former president's Florida home on Aug. 8.

"It's sickening to see the new attacks on the FBI, threatening the life of law enforcement agents and their families for simply carrying out the law and doing their job," Biden said.

"I want to say it as clearly as I can. There is no place in this country - no place - for endangering the lives of law enforcement. No place. None. Never. Period. I'm opposed to defunding the police. I'm also opposed to defunding the FBI."

Earlier this month, the FBI and U.S Department of Homeland Security warned of an increase in threats following the search of Trump's residence at Mar-a-Lago, when agents removed what prosecutors described as 11 sets of classified documents, including some marked top secret, as part of a criminal investigation.

In recent weeks, Biden has largely sidestepped conversations about the investigation, with the White House saying the Justice Department operates independently even though the risk of disclosing sensitive information has national-security implications.

Biden has sharpened his attack on members of the Republican party devoted to Trump, a theme expected to play heavily in a major prime-time address during another visit to Pennsylvania on Thursday.

"Let me tell this to my MAGA Republican friends in Congress. Don't tell me you support law enforcement if you won't condemn what happened on the 6th," he said, referring to the Jan. 6, 2021 riot by Trump supports at the Capitol.

PENNSYLVANIA CRUCIAL

Tuesday's visit to the small city of Wilkes-Barre gave Biden an opportunity to address a key concern for voters in a critical state that helped lift the Democrat to the presidency and plays host to one of the closest-watched 2022 Senate races.

Trump, who is flirting with challenging Biden for a second term in 2024, is expected to hold a rally in the same city on Saturday.

As in 2020, when Biden was elected president, Pennsylvania will be a key battleground state in the November midterms and in the next presidential election.

It is home to one of a handful of competitive Senate races that will determine whether Democrats can hold onto their razor-thin majority in the U.S. Senate.

John Fetterman, the Democratic candidate for U.S. Senate in Pennsylvania and the state's current lieutenant governor, did not join Biden for the event on Tuesday but planned to meet with him on Labor Day during his third visit to the state in a week.

Some Democratic candidates in the state and elsewhere have wrestled with whether to join Biden on the campaign trail, with some fearing his low approval ratings could drag down their campaigns.

Many Republican candidates are portraying Democrats as unwilling to fight growing crime rates in some parts of the country, trying to tie them to the "defund the police" movement that arose out of racial justice protests in 2020. Many Democrats, including Biden, have never supported slashing police funds.

The rate of U.S. gun deaths surged 35% in 2020 to the highest point since 1994, with especially deadly levels for young Black men, according to U.S. statistics published in May.

On Tuesday, Biden criticized Republican lawmakers who have opposed his plans to fund law enforcement and cut gun violence.

Biden has called for Congress to pass an assault weapons ban as well as $37 billion for crime prevention programs, with $13 billion to hire and train an additional 100,000 police officers over the next five years.

"We're living in a country awash in weapons of war," he said. "For God's sake, what's the rationale for these weapons outside of a war zone?"