“The unknown we’re facing today is much greater than the need that people believe in this aspirational bill that we’re looking at,” Manchin said Tuesday at The Wall Street Journal’s CEO Council Summit. “We’ve gotta make sure we get this right. We just can’t continue to flood the market, as we’ve done.”

Due to Republican opposition to the measure, Democrats are passing the legislation through a budgetary maneuver that lets them pass it through a simple majority vote. Because they hold such a slim majority in the Senate, Manchin’s vote is pivotal to the survival of the bill, called the Build Back Better Act.

Sen. Kyrsten Sinema (D.-Ariz.) also has expressed worries over the size of the bill in the past, but has yet to comment on whether she will support the legislation in the Senate.

Manchin’s resistance could put a hamper on Congress’ ambitious end-of-year agenda. Senate Majority Leader Chuck Schumer has reiterated that the Senate would work to pass the social spending measure before Christmas. The upper chamber of Congress also plans to address legislation on voting rights and national defense funding.

“There are more long days and nights, and potentially weekends, that the Senate will be in session this month,” he wrote in a letter to colleagues on Monday.

The House narrowly passed the Build Back Better bill in November and sent it over to the Senate. Schumer had been planning on bringing the social spending measure to a vote this week, but has pushed back the vote as the bill makes its way through the Senate committees.

Most Senate committees already have begun updating the House bill but have yet to begin the formal proofing process with the Senate parliamentarian known as “the Byrd bath,” Schumer said. This is a process through which Republican and Democratic staff argue whether to include particular provisions within the reconciliation bill.

The need to assuage Manchin and Sinema prompted Democrats to slash provisions in the bill passed by the House, a process that likely will repeat itself as the Senate works its way through the bill. Indeed, there is still vast disagreement among Democrats about some of the bill’s key provisions, including the Medicare expansion, the electric vehicle tax credit, drug pricing, and the cap on the federal deduction for state and local taxes.

Capital Alpha strategist James Lucier calculated that if the Senate doesn’t vote on Build Back Better by the Christmas recess, it likely will be pushed back to mid-February, when Congress recesses again for Presidents Day and the stopgap measure funding the government expires.

“There is no immediate danger to Triple-B if it does not fact pass before Christmas, but there is the prospect of attrition as bits get picked off during the eight-week stretch from mid-December to mid-February,” he wrote in a research note. 

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