President Joe Biden delivered a stark warning of American decline Tuesday in a speech urging Congress to vote through his ambitious infrastructure and social spending packages or lose out to the likes of China.

"These bills are not about left versus right or moderate versus progressive, or anything that pits Americans against one another," he said at a trade union training center in Howell, Michigan.

"These bills are about competitiveness versus complacency. They're about opportunity versus decay," he said. "To oppose these investments is to be complicit in America's decline."

Facing a rift in his own party -- which controls Congress with the narrowest of majorities -- and a Republican opposition aggressively blocking where it can, Biden hopes that appealing to Americans outside of Washington will give his agenda new life.

He began his speech to the blue collar audience, gathering in a swing district won by Donald Trump during the 2020 presidential election, by saying there was "a lot of noise in Washington."

President Joe Biden says Congress must pass his spending plans to keep the US competitive in the world
U.S. President Joe Biden's popularity plunged to 38 percent in a new poll. AFP / Nicholas Kamm

He then made his case for the $1.2 trillion infrastructure spending bill and a social support bill worth possibly around $2 trillion, saying that the government investment had underpinned private sector dynamism throughout US history and was now needed again.

"We led the world in research and development... but then something happened. We slowed up," Biden said. "We risk losing our edge as a nation."

He cited statistics that show US education and infrastructure have slipped far down the rankings in comparison to other advanced countries.

"Our competitors aren't waiting," he said. "In recent years, China has spent about three times as much on infrastructure as a share of their economy that we have."

Polls show that the proposals are popular.

US President Joe Biden is trying to bridge a divide between left and right in his own Democratic party
US President Joe Biden is trying to bridge a divide between left and right in his own Democratic party AFP / Nicholas Kamm

A new survey out Tuesday by Quinnipiac found 62 to 34 percent in favor of the infrastructure bill and 57 to 40 percent in favor of a social spending bill.

Citing that broad popularity, Biden says the solution should be clear.

However, with such a tight majority in Congress and such an implacable opposition, the path forward is tortuous and may yet end in failure. Just one Democrat breaking with him in the Senate or a handful in the House is enough to wreck his agenda.

Democrats are divided essentially between moderates and progressives on the size and speed of the spending proposals, with Biden trying to bridge the gap. The social support bill is already being whittled down from the progressives' previous demand for a $3.5 trillion price tag.

In Michigan he met with local congressional Representative Elissa Slotkin, one of the moderate Democrats.

Before leaving Washington, Biden held a virtual meeting with a group of other moderates. On Monday he did the same with a group representing the more leftist wing of the party.

The White House said that Monday's meeting was "constructive" and that they "discussed their shared commitment to seizing this moment to make investing in families the heart of our economic growth and competitiveness strategy."

But time is running out to pass big legislation before the focus turns to next year's midterm congressional elections, where most analysts expect to see Republicans regain control of at least one house of Congress.

The internal party wrangling comes at the same time as a row with congressional Republicans over lifting the permitted national debt limit, risking the first-ever US default.