(Bloomberg) -- President Joe Biden warned Thursday that Donald Trump leads an “extremist movement” that would undermine the nation’s institutions, as he touts efforts to protect democracy as a centerpiece of his reelection campaign.

The former president represents a group that “does not share the basic beliefs of our democracy,” and is a risk to the country, Biden said.

“There is something dangerous happening in America,” the president said. 

The location of Biden’s speech carried symbolic meaning: It was in Arizona near an institute dedicated to the late Republican Senator John McCain, a friend of Biden who denounced Trump’s brand of politics as well as autocrats worldwide.

“Not every Republican – not even the majority of Republicans – adheres to the extremist MAGA ideology,” he said. “I know it because I’ve been able to work with Republicans my whole career. But there is no question that today’s Republican Party is driven and intimidated by MAGA Republican extremists.”

Biden’s speech comes one day after Republican candidates held their second debate without Trump, who has consolidated his lead in the GOP primary on promises to use executive powers to root out federal bureaucrats who disagree with his views, carry out mass deportations of migrants and send the US military to major cities to fight crime. 

“They’re pushing the notion that the defeated former president expressed when he was in office and believes applies only to him,” Biden said of Trump and his allies. “Trump says the Constitution gave him ‘the right to do whatever he wants as president.’”

“Did you ever think you’d hear leaders of political parties in the United States of America speak like that?” Biden asked the audience.

Arizona is a battleground state where Biden beat former Trump by less than half a percentage point in 2020, fueling his political rival’s false claims the election was stolen. Funds from his 2021 stimulus package will go toward building a new presidential-style library dedicated to McCain, who was the 2008 GOP presidential nominee. Biden grew emotional as he spoke about McCain.

Biden, 80, has highlighted themes of protecting democracy often, casting Trump and his supporters as extreme and a persistent threat to US institutions. He made his case in Philadelphia’s Independence Hall ahead of last year’s midterms and at this year’s State of the Union, when he highlighted the attack on former House Speaker Nancy Pelosi’s husband by a hammer-wielding intruder who spouted conspiracy theories.

This time he called out Trump’s desires to purge the federal government and also Alabama Senator Tommy Tuberville’s blockade of military nominations over the Pentagon’s abortion policies as examples of moves that undermine the public’s faith in the rule of law.

Thursday’s address comes at a critical time in Biden’s reelection bid, as he battles low approval ratings, questions about his economic stewardship and voter concerns about his age. Polls show Biden running neck and neck with Trump in a hypothetical 2024 rematch.

Trump continues to make controversial comments, especially on his Truth Social account, where in recent weeks he has suggested that the top US general deserves execution, accused the news media of treason, attacked prosecutors and judges in criminal cases he is facing and repeated his false claims that the 2020 election was stolen.

Biden defended the general, outgoing Joint Chiefs of Staff Chairman Mark Milley, and criticized Republicans for failing to condemn “such heinous statements.”

“Democracies don’t have to die at the end of a rifle,” Biden said. “They can die when people are silent.”

Biden has stepped up his attacks on Trump, who has grown his lead as the GOP frontrunner even as he faces four criminal cases, including over his attempts to overturn the 2020 vote. Thursday’s speech was Biden’s first major address on democracy since Trump’s indictments.

The White House has sought to shine a bigger spotlight on preserving democracy, portraying Biden as an adult in the room who will steer the country away from the lawlessness represented by the Jan. 6, 2021 attack on the Capitol and the Republican Party’s infighting that has the US on a path to a government shutdown. 

It has been a potent message for Biden, motivating Democratic voters and convincing a small but crucial slice of Republicans to cross over in recent elections. But other issues threaten to overshadow it in next year’s elections. 

Concerns about democracy resonate, but surveys still show voters rank the economy, a persistent political liability for Biden, as their top issue. Biden struggled this summer to sell his economic agenda to voters who rank his handling of the issue poorly.

A mid-September Quinnipiac poll found 33% said the economy was the most important issue in deciding who to vote for as president, with preserving democracy in second place at 26%.

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