US President Joe Biden Photo: IC

Battered by critics and dire opinion polls, President Joe Biden signed into law the biggest US infrastructure revamp in more than half a century at a rare bipartisan celebration in the White House on Monday.

The $1.2 trillion package will fix bridges and roads, change out unhealthy lead water pipes, build an electric vehicle charging network, and expand broadband internet. 

It is the most significant government investment of the kind since the creation of the national highways network in the 1950s.

"We've heard countless speeches… but today we're finally getting this done," Biden told hundreds of invitees on the White House South Lawn.

"So my message to the American people is this: America is moving again and your life is going to change for the better."

Most of the crowd were Democrats but there was also a visible handful of Republicans. Notable among the Democrats were senators Kyrsten Sinema and Joe Manchin, two moderates who have warred with more left-wing members of the party, slowing down Biden's agenda.

The bill is "proof that Democrats and Republicans can come together to deliver results," Biden said. "Let's believe in one another and let's believe in America."

Infrastructure spending is popular, but the goal eluded Biden's predecessor Donald Trump for four years, turning his administration's frequent promises of an imminent

"infrastructure week" into a running joke.

Even now, Biden had to fight for months to get his squabbling Democratic Party to vote, risking a humiliating failure.

Democrats only narrowly control a bitterly divided Congress, but in a scarce moment of cooperation they were ultimately joined by a significant number of Republicans in the Senate and a symbolic handful in the House.

"We agreed this would be a truly bipartisan process," Senator Rob Portman, a Republican from Ohio, told the White House gathering. "This should be the beginning of a renewed effort to work together on big issues facing our country."

The feel-good moment may be hard to sustain.

Biden's ratings are in a downward spiral, with the latest Washington Post-ABC poll showing just 41 percent approving. Most worrying for the White House, support is ebbing away not just among the crucial independent voters but his own Democratic base.

And despite the reaching out by some Republicans, the bulk of the opposition party is in little mood to declare a truce.

Trump, who is widely expected to seek to return to the White House in the 2024 election, has savaged the 13 Republicans in the House of Representatives who voted alongside the Democrats.

He says Republicans who crossed the aisle should be "ashamed" and are not real Republicans.

AFP