Pittsburgh (AFP) - A bridge collapse Friday in Pittsburgh provided a symbolic backdrop for President Joe Biden's trip to the city to tout his $1 trillion infrastructure plan -- and try rebuilding his own crumbling approval ratings.

Arriving in the gritty city in Pennsylvania -- a key battleground state in presidential elections -- Biden motorcaded straight from Air Force One to the road bridge, which hours earlier had buckled into a snowy ravine.

"There are literally more bridges in Pittsburgh than in any other city in the world," the Democrat pronounced. "And we're going to fix them all. Not a joke -- this is going to be a gigantic change. There's 43,000 nationwide and we're sending the money."

Pittsburgh's public safety authorities tweeted that three people were hospitalized with injuries that were not life threatening. But Biden's visit threw the otherwise minor accident into the national spotlight.

In a speech later, Biden said rebuilding infrastructure, while completing a painful shift from old-school, heavy industry to high-tech jobs, would restore American economic leadership in an increasingly competitive world.

"Right here in Pittsburgh, the future is being built on the foundation of the city’s storied past," he said at a once massive steel mill, which now houses Carnegie Mellon University's Manufacturing Futures Institute -- a hub for research and development.

Flanked by "Building A Better America" signs, Biden said Pittsburgh had lost 100,000 steel jobs between 1970 and 1990 and that he knew "the painful ripple effect it had -- jobs lost, families ripped apart."

His push for investment in semiconductors, electric vehicle technology and other forward-looking products would restore that manufacturing base, he said.

"To build a truly strong economy we need a future that's made in America. That means using products, parts, materials built right here in the United States of America. It means bringing manufacturing back, jobs back, building a supply chain here at home -- not outsourcing abroad," he said.

Biden's blue collar target

Entering the second year of his administration, Biden says he hopes trips like this will help relaunch momentum ahead of November midterm elections, where Republicans are currently well poised to win control of Congress.

His speech went through many of the themes that got him elected in 2020, appealing to the blue collar voters whom former president Donald Trump and the Republicans have worked hard to lure from their historic Democratic loyalties.

In a tough first year in office, the infrastructure bill, passed with rare cross-party Republican support, was one of Biden's biggest successes. For years, presidents had failed to get Congress to revamp the sector, while Trump's repeated promises of "infrastructure week" became a running Washington joke.

But Biden has faced heavy setbacks on other priorities, most recently his attempt to get new voting rights guarantees through Congress. He is also embroiled in the standoff with Russia over Ukraine.

Despite signs of a roaring economic comeback from the Covid-19 shutdown, the recovery is proving uneven and inflation is eating into wage increases.

Biden's approval ratings have slipped to around 40 percent, making him as unpopular as Trump.

Reflecting Biden's currently dimmed political star, one important Democrat from Pennsylvania, state Attorney General Josh Shapiro, pointedly kept away from the presidential visit, citing a scheduling conflict.

However, another high profile state official, Lieutenant Governor John Fetterman, did meet with Biden at the bridge site, apparently having resolved his own previously reported scheduling conflict.

For Pittsburgh Mayor Ed Gainey, the Biden visit was certainly  welcome -- a chance to home in on the kinds of problems plaguing post-industrial cities across the country, where bridges, highways, water pipes and other basic infrastructure typically have not seen upgrades for decades.

"This is critical that we get this funding and we're glad to have the president coming today," he told CNN.