By Friday morning, it is possible that Biden’s bipartisan US$1.2 trillion infrastructure bill will have failed, imperilling a larger, US$3.5 trillion “Build Back Better” package of investments in child care, education, family leave and climate mitigation.

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Moderates want the House to wave through the Senate-passed infrastructure bill without delay, giving Biden an easy win while negotiations play out on the larger package.

But as many as 50 House progressives were expected to tank the bipartisan bill if they have no clear commitment on the larger-ticket legislation, known as the Build Back Better Act.

They argue that they’ve already compromised on the price – which started at US$6 trillion – as well as demonstrating unity on a US$1.9 trillion Covid-19 relief package that passed earlier this year.

Pelosi is always quick to frame vehement internal disagreement as “family discussion” that ultimately fosters togetherness.

But progressives have been emboldened since the election to state in increasingly stark terms their frustration over centrists they see as beholden to special interests and too keen to subjugate Democratic values to bipartisanship.

Alexandria Ocasio-Cortez, the most-high profile emissary of progressives in Washington, has urged centrist colleagues to view them as allies, not the enemy.

Ocasio-Cortez said Manchin had allowed oil industry lobbyists to dictate his climate positions and accused him of “bipartisan’ corruption that masquerades as clear-eyed moderation.”

Manchin in turn castigated the congresswoman for “just awful” rhetoric that he said had only one purpose – “divide, divide, divide”.

When top Senate Democrat Elizabeth Warren came out against Jerome Powell’s reappointment as chair of the US Federal Reserve on Tuesday she pulled no punches, calling him a “dangerous man to head up the Fed”.

And the internecine mudslinging shows no sign of cooling.

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Ilhan Omar, another progressive, suggested Monday in an interview that is sure to ruffle feathers that Manchin and other centrists balking at the high price of Build Back Better, were in the wrong party.

“It is saddening to see them use Republican talking points, we obviously didn’t envision having Republicans as part of our party,” she told CNN.

Biden, who as a six-term senator was known for his legislative savvy, has been deployed to try to resolve the intraparty rift over the size and scope of the spending package. On Tuesday, he summoned Manchin and Senator Kyrsten Sinema of Arizona for meetings at the White House in an attempt to get their agreement on elements of his economic plan.

After meeting for about 90 minutes with Biden, Manchin said he has no particular limit in mind for the spending plan.

“There were no commitments made at all,” he said. “Just good negotiations and talking about the needs of our country.”

And still unresolved is the fate of a stopgap funding measure to prevent a government shutdown after the current financial year.

Republican senators for a second time blocked a bill to keep the US government operating past Thursday and allow federal borrowing, risking a federal shutdown and devastating debt default – though both seem highly unlikely.

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Democrats said they will try again before Thursday’s deadline to pass a bill funding government operations past the September 30 financial year-end, likely stripping out the more-heated debate over the debt limit for another day, closer to a separate October deadline.

Taken together, it’s all putting the entire Biden agenda perilously closer to collapse, with consequences certain to shape his presidency and the lawmakers’ political futures.

Treasury Secretary Janet Yellen told Congress in a letter Tuesday that October 18 is a critical date – when the Treasury Department will likely exhaust all of its “extraordinary measures” being taken to avoid a default on the government’s obligations.

Yellen urged Congress to “protect the full faith and credit of the United States by acting as soon as possible” to either raise the debt limit or suspend it.

Additional reporting by Bloomberg and Associated Press