A bitterly divided Democratic party was set to resume talks on Joe Biden's legislative agenda on Friday with progressives confident they are gaining momentum and centrists apparently on the back foot.
A vote on the $1tn bipartisan infrastructure bill was delayed late on Thursday night despite a promise by the House of Representatives speaker, Nancy Pelosi, to centrists that she would bring it to the floor.
The move represented a victory for progressives who stood firm in warning that they would vote against the bill unless they get a firm commitment that Biden's $3.5tn social and environmental package will also pass.
The wrangling between the White House, Senate and House was due to resume "first thing" on Friday, the White House press secretary, Jen Psaki, said, insisting that "we are closer to an agreement than ever".
But Thursday's stalemate after long hours of negotiation exposed ideological fractures in the party, which holds razor-thin majorities in both chambers and can expect little support from Republicans.
Senator Joe Manchin of West Virginia has proposed a spending package of about $1.5tn - less than half the progressives' baseline. Another Democratic centrist, Senator Kyrsten Sinema, declined to say whether she agreed with Manchin's proposal.
Unlike the debate over Barack Obama's healthcare legislation a decade ago, progressives appear to be more closely aligned with the president and able to flex their political muscles. On Thursday they were united in making the case that centrists are now in the minority.
Pramila Jayapal, chair of the Congressional Progressive Caucus, told the MSNBC network: "Four per cent of all the Democrats in the House and Senate are blocking the Build Back Better Act from passing. Ninety-six per cent agree with us."
The point was echoed by Congresswoman Ilhan Omar and others on the party's emboldened left flank as they sought to overturn frequent media narratives that progressives are holding up the Biden agenda.
Meanwhile Manchin, Sinema and House centrists such as Josh Gottheimer seemed increasingly isolated as their hopes of passing the infrastructure deal alone slipped away.
Varshini Prakash, executive director of Sunrise Movement, a youth group fighting the climate crisis, said: "Tonight, we are so proud of progressives for holding the line. But let's be clear, progressives are not the ones delaying the vote - Joe Manchin and Kyrsten Sinema are."
Thursday's delay could anger moderates and cause further infighting that puts Biden's agenda at risk. Earlier this week Stephanie Murphy, a congresswoman from Florida, warned: "If the vote were to fail or be delayed, there would be a significant breach of trust."
Republicans who had supported the infrastructure bill in the Senate also acknowledged the setback. Senators Rob Portman, Bill Cassidy, Susan Collins, Lisa Murkowski and Mitt Romney said in a joint statement: "While we are disappointed the House of Representatives did not meet its deadline to vote on the bipartisan infrastructure bill, we remain hopeful the House will come together in a spirit of bipartisanship just as the Senate did and pass this important piece of legislation.
"This bill is critically important to modernizing and upgrading everything from our roads and bridges to broadband and increasing the resiliency of the nation's electrical grid."
The House is scheduled to leave Washington at the end of this week for a two-week recess but this could be delayed if no deal has been reached. Congress must also find a way to raise the debt ceiling to avoid the US defaulting for the first time in its history.