Democrats failed to overcome an 11th-hour revolt on US President Joe Biden's sweeping $3 trillion transport, welfare and climate agenda, as a small group of lawmakers blocked any chance of the entire package passing Friday.
Party leadership in the House of Representatives began the day aiming to rubber-stamp the Senate-passed $1.2 trillion infrastructure bill after sending an even bigger social welfare deal, worth up to $1.85 trillion, to the upper chamber.
But at least six moderate Democrats refused to commit to the Build Back Better welfare package, arguing that they first needed to see a full accounting of its economic impacts by the impartial congressional budget office (CBO), which won't be available for at least a week.
With a majority of just three votes in the House, Speaker Nancy Pelosi was forced to postpone the Build Back Better vote.
"We had hoped to be able to bring both bills to the floor today. Some members want more clarification... that (the welfare bill) is fully paid for and we honor that request," Pelosi told reporters.
Progressives, wary of thrifty centrists and desperate to see the social bill pass, have always insisted that both tracks of the two-pronged agenda move together.
Desperate for any progress to show for a day of bargaining, Pelosi offered a possible compromise of voting on the infrastructure portion Friday after at least getting debate started on Build Back Better.
But the 96-member Congressional Progressive Caucus had already ruled that out, pointing to non-partisan and White House analyses arguing that the social welfare package would "contribute to reducing the deficit."
"However, if our six colleagues still want to wait for a CBO score, we would agree to give them that time -- after which point we can vote on both bills together," the group's leader, Pramila Jayapal, said in a statement confirming a Friday vote on infrastructure was now out of the question.
Pelosi has spent days painstakingly bringing aboard holdouts over multiple sticking points in Build Back Better, from prescription drug pricing to immigration provisions.
Biden, who spent much of Thursday evening and Friday on the phone corralling lawmakers, appealed publicly for their support "right now" in a televised address from the White House.
"Let's show the world that America's democracy can deliver and propel our country forward," he said.
But the appeal fell on deaf ears, as the House failed to hold even the procedural vote necessary for debate to begin, with several of the rebels huddled with Pelosi throughout the morning.
House Majority Leader Steny Hoyer, Pelosi's deputy, was asked whether there was going to be a vote on either bill Friday as he arrived at her office.
"I don't know," he told reporters.
Pelosi has attempted twice in recent weeks to advance the twin mega-bills, but has been forced to postpone votes on infrastructure as progressives, unhappy about the lack of commitment to their priorities, refused to pledge their support.
Biden is banking on a bounce from either bill, 10 months after he swept to the White House promising the pandemic-devastated nation he would "build back better" -- only to see his popularity plunge.
His low approval ratings were blamed in part for a humiliating upset defeat this week in Virginia's gubernatorial election.
If Pelosi can persuade progressives to change their minds and vote for the infrastructure deal, it would mark an unambiguous, resounding and immediate victory for the 78-year-old former senator, who touts his ability to reach across the aisle.
By funding work on roads, bridges and ports and high-speed internet, the White House says it would create millions of high-paying jobs.
Build Back Better, on the other hand, does not have the Senate's blessing and is likely to be downsized significantly and put through further arduous votes in the upper chamber, even if it advances from the House.
"It will not be enacted as is. Everybody needs to sit with that and get comfortable with it," Montana's Democratic senator Jon Tester told Politico.
The votes will cap months of tense negotiations on Capitol Hill since the Senate approved the infrastructure package in August, giving it rare bipartisan support in Washington's polarized political atmosphere.
Most House Republicans are expected to withhold their support, however, after former president Donald Trump threatened reprisals for helping to hand Biden a political win.
And Democrats in both chambers are still haggling over the Build Back Better package that includes major investments in health, education, tackling climate change and expanding social welfare programs.