Washington (AFP) – President Joe Biden will sound the alarm on threats to US democracy in a rare prime-time address to the nation in the key swing state of Pennsylvania Thursday as his party fights to hold on to Congress in the midterm elections.

The Keystone State — which will host Biden three times in the coming days, including on Tuesday — is one of the most hotly contested battlegrounds on the midterm map.

But Republican strategists worry that controversial candidates backed by former president Donald Trump are muddying their path to victory.

The Democratic leader will echo his 2020 campaign theme about the battle for the “soul of nation” in historic Philadelphia, where the Declaration of Independence and US Constitution were written.

He will set out how an imperiled democracy threatens America's standing on the international stage, according to White House officials, highlighting action to protect voting rights but warning that access to the ballot box is still at risk.

The outcome of the upcoming Senate election in Pennsylvania could decide whether the Democrats cede control of the evenly divided upper chamber of Congress to the Republicans for the next two years.

The Cook Political Report moved the race to “lean Democrat” this month, however, citing widespread Republican concerns with Trump-backed celebrity physician Mehmet Oz's campaign.

Initially preferring to present himself as a unifier in a deeply divided country, Biden has recently been concentrating his fire on Trumpist Republicans he has accused of embracing “semi-fascism.”

Curbing violent crime

The 79-year-old Democrat, who narrowly beat Trump in Pennsylvania in 2020, will bookend Thursday's address with two other visits to the state.

Biden heads first to the city of Wilkes-Barre on Tuesday — near his hometown of Scranton — where he will promote community policing, curbing violent crime and getting guns off the streets. 

Republicans have presented themselves as the party of law-and-order amid a nationwide spike in murders — with some success, according to multiple polls — while accusing Democrats of wanting to defund the police.

But Biden recently has attempted to turn the tables by pointing to the Republicans' defense of US Capitol rioters and highlighting the various criminal investigations embroiling Trump.

The president is expected to set out his party's action on gun violence Tuesday, highlighting the bipartisan gun safety package he signed into law, as well as substantial new funding for policing.

“Every Republican lawmaker in Pennsylvania turned their backs on police and safer communities when they voted against President Biden's American Rescue Plan, which provided hundreds of billions of dollars for states to help fund law enforcement and public safety programs,” Democratic National Committee DNC spokeswoman Brooke Goren said ahead of Biden's visit.

The president is due for his third Pennsylvania stop-off in six days on Monday when he heads to Pittsburgh to celebrate Labor Day with Oz's Democratic midterm rival, John Fetterman. 

In every post-World War II midterm election, the president's party has lost an average of 26 seats in the House of Representatives and four Senate seats. 

Republicans were heavy favorites to make big gains in both chambers in this cycle but an unexpected special election victory in New York's Hudson Valley has given Democrats hope of averting a washout.   

A spate of Democratic legislative achievements has also started to pierce the consensus about a Republican wave — along with a recent drop in gas prices, stumbling Trump-backed Senate candidates in several states and a backlash to efforts to restrict abortion. 

Every seat in the House is up for election in November, while 36 of the 100 Senate spots are up for grabs — 20 of which are currently held by Republicans.