Joe Biden unveiled a sweeping $700 billion plan Thursday to help the battered US economy recover from the coronavirus crisis, a direct challenge to Donald Trump's "America First" agenda as they square off in the presidential race.

The Democratic challenger's manufacturing and innovation plan aims to bring back jobs lost during the pandemic and create more than five million new jobs by investing in domestic production and research, shrinking foreign supply chains, and promoting new tax rules and union access that empower American workers.

The six-pronged approach, which tightens "Buy America" guidelines, will be fleshed out later Thursday during a Biden speech in Dunmore, Pennsylvania where he will also tour a metal works plant. "Biden does not accept the defeatist view that the forces of automation and globalization render us helpless to retain well-paid union jobs and create more of them here in America," the campaign said in a summary of the ambitious plan.

"US manufacturing was the arsenal of democracy in World War II, and must be part of the arsenal of American prosperity today, helping fuel an economic recovery for working families."

Biden's plan aimed at protecting American workers underscores a recognition that, despite Trump's poor overall job approval numbers voters still see the president as stronger than Biden on handling the US economy. Trump won the White House in 2016 largely on the promise of bringing back lost manufacturing jobs. He also blamed immigrants for many of the nation's economic woes, and as president he fueled a trade war with China.

Biden's plan relies on what the campaign described as the "full power of the federal government to bolster American industrial and technological strength."

It proposes a $400 billion investment in domestic product procurement, and $300 billion for research and development (R&D) as well as breakthrough technologies including reusable energy and electric vehicle development and usage. "This will be the largest mobilization of public investments in procurement, infrastructure and R&D since WWII," the campaign said.

Biden's team savaged Trump for denying science, underfunding R&D, implementing a "trickle-down economics" strategy that rewards corporate executives but not working families, and introducing policies that encouraged more manufacturing to move abroad. It also warned that Trump's erratic leadership has exacerbated the coronavirus crisis and led to shortages in personal protective equipment like masks and other supplies, and said Biden would move quickly to close critical US supply chain gaps.

As president he would immediately launch a 100-day supply chain review to determine vulnerabilities in sectors like medical equipment. Biden meanwhile is deploying several of his former campaign rivals to sell his economic recovery plan.

Senator Amy Klobuchar hosts a virtual roundtable with Arizona voters on Friday, while former Indiana mayor Pete Buttigieg heads to New Hampshire to do the same.