WASHINGTON (AP) — 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. But 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 for child care and what the White House calls human infrastructure 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 taken on separately in a congressional budget process known as reconciliation, which allows for majority passage without the need for Republican votes.

Claiming a major victory five months into his presidency, Biden said, “This reminds me of the days when we used to get an awful lot done up in the United States Congress.” Biden, a former Delaware senator, said that as he put 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.

But the next steps are not likely to be nearly so smooth.

Senate Republican leader Mitch McConnell complained that Biden was “caving” to Pelosi and Senate Majority leader Chuck Schumer’s plan to “hold the bipartisan agreement hostage” for the president’s bigger package of what he called “wasteful” spending.

“That’s not the way to show you’re serious about getting a bipartisan outcome,” McConnell said.

And there is plenty of skepticism on Biden’s own left flank. 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.

Thursday’s deal was struck by the bipartisan group led by Republican Portman of Ohio and Democrat Kyrsten Sinema of Arizona, including some of the more independent lawmakers in the Senate, some known for bucking their parties.

The proposal includes both new and existing spending on long-running programs and highlights the struggle lawmakers faced in coming up with ways to pay for what have typically popular ideas.

The investments include $109 billion on roads and highways and $15 billion on electric vehicle infrastructure and transit systems as part of $312 billion in transportation spending. There’s $65 billion toward broadband and expenditures on drinking water systems and $47 billion in 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 a White House document.

Money will come from $125 billion in 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 that Portman said could yield $100 billion.