In a key test vote Wednesday evening, the Senate voted in favor of beginning debate on a $1.1 trillion bipartisan infrastructure deal that would provide funding for core items like roads, bridges, waterways and broadband.
Negotiators announced earlier in the day that they had reached a deal on the major aspects of plan.
Shortly after news broke that a deal had been reached, Senate Majority Leader Chuck Schumer announced that he would hold the test vote on the bill Wednesday, a critical first step to its passage.
Republican negotiators, all of whom blocked the procedural motion last week, said that they were ready to vote to move the bill forward and on Wednesday evening, 17 Republicans -- including Senate Minority Leader Mitch McConnell -- voted with all of the Democrats to advance the legislation, which was still being finalized. In a surprise split in the Republican leadership, McConnell's deputy, Sen. John Thune, R-S.D., voted no.
Details about the agreement were still emerging, but an aide close to the talks confirmed to ABC News that the top-line value for new spending has decreased from $579 billion in the original bipartisan agreement to $550 billion.
Sen. Rob Portman, R-Ohio, the lead Republican negotiator for the bipartisan group, said the bill is "more than paid for," an essential priority for Republicans, without raising taxes on those making under $400,000 a year, a red line for President Joe Biden.
The deal includes $110 billion in new funds for roads and bridges, $66 billion for rail, $7.5 billion to build out electric vehicle charging stations, $17 billion for ports, $25 billion for airports, $55 billion for clean drinking water, a $65 billion investment in high-speed internet and more.
Sen. Kyrsten Sinema, D-Ariz., the chief Democratic negotiator, told reporters that she expects some of the bill text to be available Wednesday with further updates released as the remaining details are worked out.
A "small, tiny thing" related to transit and a "small thing" related to broadband must still be addressed, Sinema said, adding that negotiators are "very excited" to have a deal.
Sinema said she spoke with Biden and said he too is "very excited" about and "committed to" the plan.
Biden released a statement Wednesday afternoon hailing the deal as a signal to the world that "our democracy can function, deliver, and do big things."
"As the deal goes to the entire Senate, there is still plenty of work ahead to bring this home," Biden wrote. "There will be disagreements to resolve and more compromise to forge along the way."
Portman announced the agreement flanked by the four other Republicans in the core negotiating group early Wednesday afternoon.
"As of late last night and really early this morning we now have an agreement on the major issues we are prepared to move forward," Portman said. "We look forward to moving ahead and having the opportunity to have a healthy debate here in the chamber regarding an incredibly important project to the American people."
Sen. Susan Collins, R-Maine, who was part of the bipartisan negotiation group, touted the deal as a much-needed signal that bipartisanship is possible, even in an evenly divided Senate.
"I am delighted that we've been able to come together as a bipartisan group," Collins said. "America needs to see us be able to tackle an important issue that will affect the lives of Americans throughout this country."
It's still not clear if all Democrats are going to support the bipartisan deal. Sen. Dick Durbin of Illinois, the Democratic whip, said Wednesday morning that was an "unanswered question."
"We certainly don't have a whip or people signing on the dotted line," Durbin said. "We need some assurances that we are all in this together."
Wednesday's test vote in the Senate was expected to be the first in a long series of hurdles to pass this bill and Biden's other agenda priorities. In addition to the procedural hurdles which still threaten to trip up the bipartisan deal on the floor, Democrats are also working to push through a second, larger budget bill containing the remainder of Biden's American Families Plan priorities along party lines.
Schumer has long insisted that both the budget bill and the bipartisan bill need to pass together using a "two-track" approach.
But Sinema threatened to derail that plan on Wednesday, announcing in a press release that she won't support spending the $3.5 trillion that Budget Committee Democrats agreed to as a top line for the budget bill.
"I have told Senate leadership and President Biden that I support many of the goals in this proposal to continue creating jobs, growing American competitiveness, and expanding economic opportunities for Arizonans," Sinema said. "I have also made clear that while I will support beginning this process, I do not support a bill that costs $3.5 trillion -- and in the coming months, I will work in good faith to develop this legislation with my colleagues and the administration to strengthen Arizona's economy and help Arizona's everyday families get ahead.”
To pass the budget bill, Democrats will need the support of every Democrat serving in the Senate. Sinema's opposition points to the possibility of a long road ahead for many of Biden's infrastructure priorities.
ABC News' Molly Nagle contributed to this report.