(WASHINGTON) — The House could vote as soon as Thursday evening on the second piece of President Joe Biden’s infrastructure improvement agenda — the largest expansion of the nation’s social safety net in 50 years — House Speaker Nancy Pelosi said.

As Democrats barrel ahead towards a vote, with the chamber already starting debate on the “Build Back Better Act” Thursday morning, the nonpartisan Congressional Budget Office said it would release its final estimate on the cost of the total package in the afternoon.

Pelosi, D-Calif., told reporters at a Capitol Hill news conference that the outstanding information would “hopefully” be released by 5 p.m., clearing the way for a vote on final passage later in the evening. Democratic moderates had promised progressives they would commit to voting for the social spending bill the week of Nov. 15 if the CBO provided more “fiscal information” to satisfy their cost concerns.

The social spending bill contains $555 billion for climate and clean energy investments. It would reduce the cost of some prescription drugs, extend the child tax credit, expand universal preschool and includes electric-vehicle tax credits, paid leave, housing assistance and dozens more progressive priorities.

The vote on the package could be pushed to Friday so to give lawmakers more time to review the cost estimates, but Pelosi presented a timeline that could send House lawmakers home to their Thanksgiving recess as scheduled.

“As soon as we get the scrub information we can proceed with our manager’s amendment to proceed to a vote on the new rules, the manager’s amendment, reflecting the scrub, not any policy changes, but just some technicalities about committee jurisdiction, etc.,” she said. “And then we will vote on the rule and then on the bill. Those votes hopefully will take place later this afternoon.”

The House vote would then send the package to the Senate, which is expected to amend the proposal in the coming weeks after the Thanksgiving recess as Democratic Sen. Kyrsten Sinema and Joe Manchin have not committed to the package in its current form.

Since Democrats plan to pass the measure through reconciliation, a lengthy budget process that would not require them to have any Republican support since Democrats have a narrow majority in both chambers, the legislation — months in the making — still has a long way to go, including back to the House, before it would even hit Biden’s desk.

Pelosi expressed confidence that with control of Congress hanging in the balance ahead of the midterm elections less than a year away, Democrats will be able to successfully sell their work to the American people — and do so more effectively than they did in 2010 after the passage of the Affordable Care Act, due, in part, to Biden using the “bully pulpit.”

“Joe Biden is very committed to messaging this. As you’ve seen he’s already on the road,” she said. “There’s no substitute for the bully pulpit of the president of the United States reinforced by the events we will have across the United States.”

Democratic members of Congress are also planning to hold 1,000 events before the end of the year to make clear to Americans “what we’re doing in this package,” according to the chair of the Democratic Congressional Campaign Committee, Rep. Sean Patrick Maloney of New York, speaking to part one of Biden’s policy agenda on infrastructure signed into law on Monday.

“The messaging on it will be immediate, and it will be intense, and it will be eloquent, and it will make a difference,” Pelosi said.

Giving remarks in Woodstock, New Hampshire, on Tuesday, Biden also endorsed Pelosi’s timeline to pass part two of his infrastructure agenda this week.

“I’m confident that the House is going to pass this bill. And when it passes, it will go to the Senate,” Biden said. “I think we’ll get it passed within a week.”

House Minority Leader Kevin McCarthy, in his quest to become the House speaker, blasted Pelosi at his press conference and said the reconciliation bill will “be the end of their Democratic majority.”

While the already-passed bipartisan infrastructure law itself and its individual components — rebuilding and repairing bridges, ports and roads, expanding broadband internet, and more — are widely popular, a new ABC News/Washington Post poll shows Americans aren’t giving Biden credit for championing the law and getting it through Congress. The president’s approval rating is at an all-time low at 41%.

Democratic leaders and the White House continue to insist both pieces of legislation will be fully paid for, in part by imposing a 15% minimum tax on corporate profits that large corporations report to shareholders.

Pelosi on Thursday also tried to defend Democrats’ “Build Back Better” proposal from criticism over a key tax provision that has angered some in the caucus. Some moderates and leading progressives have criticized plans to undo a cap on the state and local tax (SALT) deductions — a reversal of Republicans’ 2017 tax law — popular in California, New York and New Jersey, given that the change would benefit wealthy suburban property owners.

The change would allow taxpayers to deduct up to $80,000 in state and local taxes from their federal tax returns after Republicans imposed a $10,000 cap on federal deductions four years ago.

A recent analysis from the Toxic Policy Center found the SALT cap increase would primarily benefit the top 10% of income-earning Americans. About 70% of the tax benefit would go to the top 5% of earners, who make $366,000 a year or more, the analysis said.

“That’s not about tax cuts for wealthy people. It’s about services for the American people,” Pelosi said. “This isn’t about who gets a tax cut, it’s about which states get the revenue they need to help the American people.”

ABC News’ Trish Turner and Mariam Khan contributed to this report.

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