A large bipartisan majority in a highly divided Senate has backed the bill in two procedural votes, but no legislator has seen the final text.
Votes in the Senate have so far focused on a framework bill that will incorporate the specific law once it is completed.
The Senate voted 66-28 in favor of the bill on Friday, with 16 Republicans joining 48 Democrats and two independents. The Senate also called an unusual session on Saturday.
The massive infrastructure package is President Joe Biden’s top legislative priority.
In addition to the $ 450 billion previously approved, the package is expected to include $ 550 billion in new spending and dramatically increase investment in roads, bridges and airports.
His supporters, including Senate Democratic Leader Chuck Schumer and Senate Republican Leader Mitch McConnell, have been optimistic about the chances of the bill becoming law.
The initiative does not include funding for climate change and social proposals, which the progressive wing of the Democratic Party has pushed.
Democrats have included those measures in another $ 3.5 trillion package, which they will attempt to pass without Republican support.