House Democrats are poised Thursday to approve a huge boost in infrastructure spending, a $715 billion proposal they view as a vehicle to install some of their own policy preferences into an evolving $973 billion Senate package that stands among President Biden’s top priorities.

The House bill is designed not only to shore up the nation’s aging roads and bridges, but also to realign its public works programs to confront a warming planet.

It packages new surface transportation spending with efforts to modernize the nation’s water systems, but addresses only parts of the broader, bipartisan infrastructure framework being crafted in the Senate. House Democrats are trying to influence that legislation before it is even written, urging the Senate to adopt parts of their bill.

“I’m suggesting that substantial amounts of the policy in our bill should be negotiated — by the White House and the Senate and the House — to be part of that bipartisan proposal,” said Rep. Peter DeFazio (D-Ore.), chairman of the House Transportation and Infrastructure Committee.

Thursday’s House vote arrives at a delicate time in the infrastructure debate. Biden, after announcing a bipartisan deal, had snarled the talks by appearing to threaten a veto of the same bill if it wasn’t accompanied by a larger, Democratic package of social benefit programs.

Over the weekend, Biden walked back the threat, which appeased some of the moderate Republican senators who’d initially endorsed the deal. But others remain skeptical, particularly since Speaker Nancy Pelosi (D-Calif.) has also vowed to link the two proposals — and unlike Biden, she’s sticking to it.

“The statement I made is the statement I stand by,” she said Wednesday.  

DeFazio and Pelosi both praised the spending levels outlined in the Senate agreement — levels that DeFazio described as “within shouting distance” of winning House support. But the absence of certain policy provisions in the Senate’s rough framework has given House Democrats an opening to solicit changes.

Rep. Frank Pallone Jr. (D-N.J.), chairman of the Energy and Commerce Committee, noted two glaring differences: The House proposal would establish tougher new water quality standards, and create a permanent safety net program to help low-income people pay water bills. Neither is in the Senate proposal. 

“But you could conference or work between the two houses on that,” Pallone said.

Timing is also playing into the debate. DeFazio noted that it took his committee staff seven months to draft the nuanced policy provisions of his massive proposal. To expedite the process of getting a bill to Biden’s desk, he’s urging Senate Majority Leader Charles Schumer (D-N.Y.) to drop any plans for the Senate to write its own legislative text and enter into “informal” negotiations with House lawmakers — rather than creating a formal conference committee — to adopt some of the House language.

“If they want to dispatch of this quickly — and they’re talking about July, which is a very, very quick timeline if you’re trying to negotiate policy in any major way,” DeFazio said, “then I would suggest it would probably be a much quicker, more informal process.”

The other significant difference between the chambers is that the Senate bill has proposed offset provisions to help cover the enormous cost of their framework. The House is leaving those details for another day, but wants to move swiftly on their proposal, not least because the federal surface transportation funding expires on Oct. 1, the end of the current fiscal year, and needs reauthorizing before then.

“There’s a sense of urgency about surface, because we have a deadline,” said DeFazio.

The House package set to get a vote Thursday is largely devoted to surface transportation projects, with designs not only to repair and replace dilapidated highways and bridges, but also to reimagine transit in an age of global warming. Toward that end, the bill features provisions designed to promote a shift to electric vehicles, compel states to find alternatives to expanding highways, and requiring new construction to use more environmentally friendly materials.

“We have a new existential challenge, which is climate change,” said DeFazio, noting the recent heat wave in the region he represents. “So, we have to rebuild in ways we never even thought about before. It’s going to be expensive. But the good news is it is going to create millions — millions — of good-paying jobs.”

Pelosi characterized the shift to greener technologies and mass transit as a “once-in-a-century opportunity” to revamp the nation’s infrastructure with a sustainable environment in mind — an investment, she said, that will pay for itself.

“The most expensive maintenance is no maintenance at all,” she said.

The proposal is expected to pass easily through the House on Thursday, though without any significant support from Republicans.