WASHINGTON (NYTIMES) - US President Joe Biden hosted a series of meetings on Wednesday (Sept 22) with Democratic lawmakers, including party leaders, as he worked to smooth over deep divisions within his party about his multi-trillion-dollar domestic agenda.

In a series of Oval Office meetings that continued throughout the afternoon, Mr Biden huddled with the two top Democrats, House Speaker Nancy Pelosi of California and Senator Chuck Schumer of New York, the Senate majority leader, and separately with nearly two dozen lawmakers from across the ideological range of his party.

The flurry of meetings came as both pieces of his economic agenda - a US$1 trillion (S$1.35 trillion) bipartisan infrastructure Bill and a second, expansive US$3.5 trillion social safety net package that supporters intend to push through with only Democratic votes - appear to be on a collision course, with moderate and liberal Democrats jockeying for leverage in a narrowly divided Congress.

In essence, Mr Biden's entire agenda faces a make-or-break moment, with an array of policy disagreements - over how large the domestic policy package should be and how to pay for and structure the programmes it funds - standing in the way of action on any of it.

Speaking at her daily news conference, Ms Jen Psaki, the White House press secretary, said that as the voting on the economic legislation neared, "there needs to be a deeper engagement by the president. That's what you're seeing happen today."

Mr Biden, she said, "sees his role as uniting and as working to bring together people over common agreement and on a path forward."

The lawmakers invited to negotiate with Mr Biden in the Oval Office on Wednesday included centrist Representatives Josh Gottheimer of New Jersey, Mr Mike Thompson of California and Ms Stephanie Murphy of Florida, as well as Representative Pramila Jayapal, the chairwoman of the Congressional Progressive Caucus.

Senators Bernie Sanders, the liberal independent from Vermont who chairs the Senate Budget Committee; Mr Ron Wyden of Oregon, the chairman of the Finance Committee; and Ms Patty Murray of Washington, a member of Democratic leadership, were also slated to head to the White House, as were Senators Jon Tester, from conservative-leaning Montana, and Mr Mark Warner of Virginia.

Senators Joe Manchin III of West Virginia and Ms Kyrsten Sinema of Arizona, centrists who have balked at the price tag of the social safety net plan, also planned to attend, according to their offices.

"We've got to do some negotiating moving forward," Mr Tester said on Wednesday. "I don't think that's a big secret."

Liberal Democrats in the House remain adamant that they will withhold their votes for the infrastructure Bill, which passed the Senate earlier this year, until that chamber approves the US$3.5 trillion package.

Without the liberals' backing, Democrats are almost certain to fall short of the votes they need to win approval of the infrastructure measure in the House, where Ms Pelosi has committed to bringing it up by Monday.

Returning to the Capitol after meeting with Mr Biden, neither Ms Pelosi nor Mr Schumer shared many details about the discussions, although they projected confidence that Congress would be able to deliver the measures.

"We are on schedule - that's all I will say," Ms Pelosi told reporters. "We're calm, and everybody's good and our work's almost done."

Representative Ro Khanna said Wednesday morning that liberals could not negotiate a final package if more conservative Democrats would not present a counteroffer to the US$3.5 trillion measure they have agreed to.

For weeks, progressives have insisted that their support for the infrastructure package was contingent on the scope and success of the larger package, which carries most of their ambitions.

Democrats plan to push through that Bill under a fast-track budget process known as reconciliation that shields it from a filibuster, but because of their slim margins of control in the House and Senate, it can only pass if virtually every member of their party supports it.

With Ms Sinema and Mr Manchin warning that they will not back a package so large, and moderates in the House reluctant to vote on a measure that will not become law, Ms Pelosi has said she will not proceed with infrastructure Bill until it is clear what the Senate can pass.