US President Joe Biden paid a rare visit to Capitol Hill on Friday to lobby for an approximately $1 trillion (€862 billion) infrastructure bill.

The plan has already passed in the Senate with bipartisan support.

But progressive and moderate Democrat lawmakers reached an impasse in a row over spending.

"It doesn't matter whether it's six minutes, six days or six weeks, we're going to get it done," Biden told reporters as he left a closed-door meeting with Democrat lawmakers at the Capitol.

"We are going to deliver for the American people," Biden's official Twitter account posted following the meeting.

What is the infrastructure bill?

The bill will see investments in public transport, including in trains, the White House outlined on its official website. Clean drinking water and wastewater infrastructure also feature in the plan.

Other areas of investment include building high-speed internet infrastructure and plans to tackle climate change. The bill outlines plans to enable clean energy transmission and electric vehicles, as well as build a clean, updated electric grid.

Why aren't Democrats backing the bill?

Progressive and moderate democrats are at odds over a separate social spending and climate change bill that Biden also wants to pass.

Progressives want around $3.5 trillion to be spent on education, childcare, and promoting clean energy. But moderates say that bill is too expensive, and are seeking around $2 trillion spent on this instead.

The row has seen members of the party's progressive wing vow to block the $1 trillion infrastructure bill to maintain negotiating leverage.

They say they will only back the infrastructure plan once the Democratic-controlled Senate backs the original social spending deal.

Key points from Biden's meeting

During the private meeting with House Democrats, the president acknowledged that his party currently did not have enough votes to pass the two spending bills, lawmakers said.

Biden reportedly told Democrats that he wanted both bills passed regardless of how long it takes.

Biden allegedly discussed a compromise topline of $1.9 trillion to $2.3 trillion, the AP news agency reported quoting a person in the room who was granted anonymity to discuss the talks.

What happens next?

Shortly after Biden's 40-minute meeting, Nancy Pelosi, the leader of the fractious House Democrats, pulled a vote on the bill again, after delaying a vote on the plan on Thursday.

The move buys time for crafting an overall agreement on the two bills. But there is no hard timeline for action on either bill.

kmm/fb (AFP, AP, Reuters)