WASHINGTON (NewsNation Now) —  President Joe Biden announced on Thursday a hard-earned bipartisan agreement on a pared-down infrastructure plan that would make a start on his top legislative priority and validate his efforts to reach across the political aisle. He openly acknowledged that Democrats will likely have to tackle much of the rest on their own.

The bill’s price tag at $973 billion over five years, or $1.2 trillion over eight years, is a scaled-back but still significant piece of Biden’s broader proposals.

It includes more than a half-trillion dollars in new spending and could open the door to the president’s more sweeping $4 trillion proposals later on.

“When we can find common ground, working across party lines, that is what I will seek to do,” said Biden, who deemed the deal “a true bipartisan effort, breaking the ice that too often has kept us frozen in place.”

The president stressed that “neither side got everything they wanted in this deal; that’s what it means to compromise,” and said that other White House priorities would be tackled separately in a congressional budget process known as reconciliation

He made clear that the two items would be done “in tandem” and that he would not sign the bipartisan deal without the other, bigger piece. Progressive members of Congress declared they would hold to the same approach.

“This reminds me of the days when we used to get an awful lot done up in the United States Congress,” said Biden, a former Delaware senator, putting his hand on the shoulder of a stoic-looking Republican Sen. Rob Portman as the president made a surprise appearance with a bipartisan group of senators to announce the deal outside the White House.

“We’ve struck a deal,” Biden then tweeted. “A group of senators – five Democrats and five Republicans – has come together and forged an infrastructure agreement that will create millions of American jobs.”

The senators have struggled over how to pay for the new spending but left for the White House with a sense of confidence that funding issues had been addressed.

Biden unveiled the first phase of his “Build Back Better” package in March, which would have spent $2.3 trillion on four main hard infrastructure categories — transportation; public water, health and broadband systems; community care for seniors; and innovation research and development.

The major hurdle for a bipartisan agreement has been financing. Biden demanded no new taxes on anyone making less than $400,000, while Republican lawmakers were unwilling to raise taxes beyond such steps as indexing the gasoline tax to inflation. But senators departed for the White House Thursday with a sense of confidence that funding issues had been addressed.

The deal was struck after months of partisan rancor that has consumed Washington while Biden has insisted that something could be done despite skepticism from many in his own party. Led by Republican Portman of Ohio and Democrat Kyrsten Sinema of Arizona, the group included some of the more independent lawmakers in the Senate, some known for bucking their parties.

“You know there are many who say bipartisanship is dead in Washington,” said Sinema, “We can use bipartisanship to solve these challenges.”

“We’re still refining the details, but from my perspective, it is paid for,” said Maine Sen. Susan Collins, a Republican and one of 10 lawmakers who met with Biden for roughly 30 minutes.

The investments include $109 billion on roads and highways, $15 billion on electric vehicle infrastructure and transit systems and $65 billion toward broadband, among other expenditures on airports, drinking water systems and resiliency efforts to tackle climate change.

Rather than Biden’s proposed corporate tax hike that Republicans oppose or the gas tax increase that the president rejected, funds will be tapped from a range of sources — without a full tally yet, according to the White House document.

Money will come from COVID-19 relief funds approved in 2020 but not yet spent, as well as untapped unemployment insurance funds that Democrats have been hesitant to poach. Other revenue is expected by going harder after tax cheats by beefing up Internal Revenue Service enforcement.

The rest is a hodge-podge of asset sales and accounting tools, including funds coming from 5G telecommunication spectrum lease sales, strategic petroleum reserve and an expectation that the sweeping investment will generate economic growth — what the White House calls the “macroeconomic impact of infrastructure investment.”

Biden has sought $1.7 trillion in his American Jobs Plan, part of nearly $4 trillion in broad infrastructure spending on roads, bridges and broadband internet but also including the so-called care economy of child care centers, hospitals and elder care.

With Republicans opposed to Biden’s proposed corporate tax rate increase, from 21% to 28%, the group has looked at other ways to raise revenue. Biden rejected their idea to allow gas taxes paid at the pump to rise with inflation, viewing it as a financial burden on American drivers.

The broad reconciliation bill would likely include tax increases on the wealthy and corporations, so tension still exists over funding for some Republicans and business groups. The U.S. Chamber of Commerce came out Thursday applauding the bipartisan infrastructure agreement, but Neil Bradley, its executive vice president, warned that “some in Congress are trying to torpedo the deal” unless they get trillions in additional spending.

There is still some skepticism on the left. Sen. Richard Blumenthal of Connecticut said the bipartisan agreement is “way too small –paltry, pathetic. I need a clear, ironclad assurance that there will be a really adequate robust package” that will follow the bipartisan agreement.

House Speaker Nancy Pelosi, like Biden, warned that it must be paired with the president’s bigger goals now being prepared by Congress under a process that could push them through the Senate with only Democratic votes.

“There ain’t going to be a bipartisan bill without a reconciliation bill,” Pelosi said.

Portman had met privately ahead of the White House meeting with Senate Republican leader Mitch McConnell at the Capitol and said afterward that the Kentucky senator “remains open-minded and he’s listening still.”

This story is developing. Refresh for updates.

The Associated Press and Reuters contributed to this report.