President Joe Biden says the US is “on the move again” and ready to lead the world in the face of the challenge presented by autocratic rivals.

Speaking on the eve of his 100th day in office, Mr Biden appeared in the chamber of the US House of Representatives on Wednesday (local time) at an event scaled back because of the COVID-19 pandemic.

He removed his mask to speak to a small group of assembled Democratic and Republican lawmakers, other officials and guests.

Mr Biden’s speech, delivered to an audience of millions watching on television, outlined his progressive vision for America.

He outlined the need to rebuild after the pandemic to advance Democratic priorities at a time of political polarisation.

“America is ready for a take-off,” he said.

“Now, after just 100 days, I can report to the nation: America is on the move again, turning peril into possibility, crisis into opportunity, setback into strength.”

“We are working again, dreaming again, discovering again, leading the world again.”

He argued that a new spending and tax-credit package, which together with an earlier infrastructure and jobs plan, totals about $US4 trillion ($A5.1 trillion), rivalling the annual federal budget – is a once-in-a-generation investment vital to America’s future.

Tweet from @POTUS

“Tonight, I come to talk about crisis — and opportunity,” he said. “About rebuilding our nation — and revitalising our democracy. And winning the future for America.”

Mr Biden argued that the spending plans were needed to keep up with China, which his administration sees as a major strategic challenger.

“China and other countries are closing in fast,” he said.

He said he had spent a lot of time talking to Chinese President Xi Jinping.

“He’s deadly earnest about becoming the most significant, consequential nation in the world. He and others, autocrats, think that democracy can’t compete in the 21st century with autocracies. It takes too long to get consensus,” he said.

Mr Biden is trying to thread the needle between Republicans opposed to more spending and the tax increases needed to pay for it, and liberal Democrats who believe Mr Biden needs more aggressive plans.

The Democratic President spoke of a willingness to speak with lawmakers on both sides of the aisle to come to an agreement. He will meet top Democratic and Republican lawmakers at the White House on May 12 to try to find common ground.

His plan includes $US1 trillion ($A1.3 trillion) in spending on education and childcare over 10 years and $US800 billion ($A1.0 trillion) in tax credits aimed at middle- and low-income families, according to a White House fact sheet. It also includes $US200 billion ($A257 billion) for free, universal preschool and $US109 billion ($A140 billion) for free community college regardless of income for two years, the White House said.

The plan would be paid for by tax increases on high-income earners and corporations.

The American Families Plan and the infrastructure and jobs plan the White House introduced this month could represent the most significant government transformation of the economy in decades.

Mr Biden’s address was groundbreaking, as two women – Vice-President Kamala Harris and House Speaker Nancy Pelosi – sat behind the president for the first time in US history.

Mr Biden spoke a little more than three months after protesters loyal to then-President Donald Trump stormed the US Capitol, a deadly incident that shook America and led to security fencing that still remains outside the building.

Republican US Senator Tim Scott is due to argue in his rebuttal to Biden’s speech that the President’s proposals are “socialist dreams” that will hamper long-term economic growth.

-with AAP