The US Senate will vote on Wednesday on whether to move forward on a $1.2tn bipartisan infrastructure deal after negotiators reached agreement on the major components of the package that is a key priority of Joe Biden.

The agreement, which follows months of talks between Senate Democrats and Republicans, is expected to gain strong support from lawmakers on both sides of the party aisle.

Biden promised to work with members of both parties to ensure the bill’s passage “because while there’s a lot we don’t agree on, I believe that we should be able to work together on the few things we do agree on. I think it’s important.”

The top Senate Democrat, Chuck Schumer, told reporters on Capitol Hill that he would call a procedural vote on Wednesday to move forward on the measure and that he believed there were enough senators in agreement to pass it. Republicans blocked a similar move last week, saying that the details of the deal had not yet been nailed down.

Democratic senator Kyrsten Sinema and Republican senator Rob Portman, the two lead Senate negotiators, announced the agreement to reporters in the Capitol. Details on transit and broadband were still being finalized.

“We’re excited to have a deal,” Sinema said. “We’ve got most of the text done, so we’ll be releasing it and then we’ll update it as we get those last pieces finalized.”

The bipartisan bill is a key component of Biden’s larger domestic policy agenda. Democrats plan to address the remainder with a sweeping $3.5tn reconciliation package that Republicans have vowed to oppose.

However, there were still signs of potential trouble for the bipartisan infrastructure bill on Wednesday afternoon, after Sinema said she does not support the price tag of the separate reconciliation bill, which would fund many of Biden’s “human infrastructure” initiatives championed by progressives in his party.

“Good luck tanking your own party’s investment on childcare, climate action, and infrastructure while presuming you’ll survive a three-vote House margin – especially after choosing to exclude members of color from negotiations and calling that a “bipartisan accomplishment,” progressive congresswoman Alexandria Ocasio-Cortez of New York tweeted.

“Without a reconciliation package that meets this moment, I’m a no on this bipartisan deal,” tweeted Mondaire Jones, the progressive congressman who represents parts of the Bronx.

Some Senate progressives have indicated they will vote in favor of the bipartisan bill only if their moderate colleagues help them pass the reconciliation package.

Democrats also have an extremely narrow margin in the House, which could create hurdles for the passage of the bipartisan infrastructure bill if progressives oppose it.

The infrastructure bill will propose $550bn in new spending, down from $579bn in a framework the negotiators sketched out several weeks ago.

Addressing a concern over funding among Republican lawmakers including Senate minority leader Mitch McConnell, Portman said the package is “more than paid for” and added: “We look forward to moving ahead and having a healthy debate.”

It scraps previous plans to spend $20bn to create an infrastructure financing authority, sources in both parties said. It had been intended to attract investment through private-public partnerships, but Republicans opposed Democratic demands designed to lift worker wages by attaching requirements that contractors pay prevailing wages, typically higher levels secured by unions.

Four other Republican negotiators joined Portman, including Senator Lisa Murkowski, who said the agreement showed Republicans and Democrats in the sharply divided US Congress “can come together over really hard stuff to negotiate in good faith to broker an agreement”.

The agreement includes $110bn for roads, $65bn to expand broadband access and $47bn for environmental resiliency, the lawmakers said.

Before the announcement, Murkowski told reporters: “I think that there is a strong, solid number of folks on both sides of the aisle that want to get on to an infrastructure package.”

Reuters contributed to this report