WASHINGTON — After much delay, senators unveiled a nearly $1 trillion bipartisan infrastructure package, wrapping up days of painstaking work on the inches-thick bill and launching what is certain to be a lengthy debate over President Joe Biden’s big priority.

The Infrastructure Investment and Jobs Act clocked in at some 2,700 pages, and senators could begin amending it soon. Despite the hurry-up-and-wait during a rare weekend session, emotions bubbled over once the bill was produced Sunday night. The final product was not intended to stray from the broad outline senators had negotiated for weeks with the White House.

“We haven’t done a large, bipartisan bill of this nature in a long time,” said Senate Majority Leader Chuck Schumer, D-N.Y. He said a final vote could be held “in a matter of days.”

A key part of Biden’s agenda, the bipartisan bill is the first phase of the president’s infrastructure plan. It calls for $550 billion in new spending over five years above projected federal levels, what could be one of the more substantial expenditures on the nation’s roads, bridges, waterworks, broadband and the electric grid in years.

A Long and Difficult Process

Senators and staff labored behind the scenes for days to write the massive bill. It was supposed to be ready Friday, but by Sunday, even more glitches were caught and changes made.

Late Sunday, most of the 10 senators involved in the bipartisan effort rose on the Senate floor to mark the moment.

“We know that this has been a long and sometimes difficult process, but we are proud this evening to announce this legislation,” said Sen. Kyrsten Sinema, D-Ariz., a lead negotiator. The bill showed “we can put aside our own political differences for the good of the country,” she said.

Sen. Rob Portman of Ohio, a Republican negotiator, said the final product will be “great for the American people.”

Over the long weekend of starts and stops, Schumer repeatedly warned that he was prepared to keep lawmakers in Washington for as long as it took to complete votes on both the bipartisan infrastructure plan and a budget blueprint that would allow the Senate to begin work later this year on a massive, $3.5 trillion social, health and environmental bill.

Package to Be Financed By Unused COVID and Unemployment Aid

Among the major new investments, the bipartisan package is expected to provide $110 billion for roads and bridges, $39 billion for public transit and $66 billion for rail. There’s also set to be $55 billion for water and wastewater infrastructure as well as billions for airports, ports, broadband internet and electric vehicle charging stations.

The spending is broadly popular among lawmakers, bringing long-delayed capital for big-ticket items that cities and states can rarely afford on their own.

Paying for the package has been a challenge after senators rejected ideas to raise revenue from a new gas tax or other streams. Instead, it is being financed from funding sources that might not pass muster with deficit hawks, including repurposing some $205 billion in untapped COVID-19 relief aid, as well as unemployment assistance that was turned back by some states and relying on projected future economic growth.

“I’ve got real concerns with this bill,” said Sen. Mike Lee, R-Utah.

Bipartisan Support Helped Push Process Forward

Bipartisan support from Republican and Democratic senators pushed the process along, and Schumer wanted the voting to be wrapped up before senators left for the August recess.

Last week, 17 GOP senators joined all Democrats in voting to start work on the bipartisan bill. That support largely held, with Senate Minority Leader Mitch McConnell, R-Ky., voting yes in another procedural vote to nudge the process along in the 50-50 Senate, where 60 votes are needed to overcome a filibuster and advance legislation.

Whether the number of Republican senators willing to pass the bill grows or shrinks in the days ahead will determine if the president’s signature issue can make it across the finish line.

Sen. John Cornyn, R-Texas, said he expects Schumer to allow all senators to have a chance to shape the bipartisan bill and allow for amendments from members of both parties.

“I hope we can now pump the brakes a little bit and take the time and care to evaluate the benefits and the cost of this legislation,” Cornyn said.

The bipartisan bill still faces a rough road in the House, where progressive lawmakers want a more robust package but may have to settle for this one to keep Biden’s infrastructure plans on track.

The outcome with the bipartisan effort will set the stage for the next debate over Biden’s much more ambitious $3.5 trillion package, a strictly partisan pursuit of far-reaching programs and services including child care, tax breaks and health care that touch almost every corner of American life. Republicans strongly oppose that bill, which would require a simple majority for passage. Final votes on that measure are not expected until fall.