Democrats and Republicans are racing to revise key components of an approximately $250 billion bill to boost U.S. science and technology, proffering last-minute tweaks that threaten to dramatically alter the bipartisan measure — and set the tone of the Senate’s work in the months to come.

Lawmakers had envisioned their proposal, now known as the United States Innovation and Competition Act, as a widely backed way to put new economic pressure on China — while helping to give the United States an edge in producing high-power computer chips and other cutting-edge tools seen as critical to the digital age.

But shepherding the bill to passage appears to be no easy task for Senate Majority Leader Charles E. Schumer (D-N.Y.), one of its chief sponsors. He has opened the measure to amendments in an attempt to build broad political support, yet Democrats and Republicans alike have filed hundreds of potential changes that could reshape the bill — or hamstring its prospects.

The latest came Monday from Sen. Bernie Sanders (I-Vt.), who pledged to take aim at two of the bill’s key components. He proposed strict new limits on a roughly $53 billion fund that would bolster U.S. chipmakers, seeking to ensure companies that receive the aid don’t use it to buy back their own stock or pad executive pay.

Sanders also sought to eliminate a new, $10 billion lunar-landing effort that widely is seen to benefit Blue Origin, the space company run by Amazon founder Jeff Bezos. (Bezos also owns The Washington Post.) The provision was included in the legislation at the behest of Sen. Maria Cantwell (D-Wash.), the chairwoman of the Senate Commerce Committee, who represents the state where Blue Origin is based.

David Strickland, the staff director for the panel, said in a statement late Monday that the provision reflects a “best practice” at NASA to ensure “resiliency and redundancy” in its space programs. “This bipartisan language follows that successful blueprint for NASA missions," he said.

Republicans similarly have filed a barrage of amendments, reflecting the party’s growing desire to make the bill even tougher on China, that Democrats might find problematic. Sen. Marco Rubio (R-Fla.), for example, has pushed a series of changes that he says would ensure that research and technology funded by U.S. dollars didn’t ultimately benefit Chinese companies.

The flurry of freshly proposed changes reflects the tall political order facing Senate Democrats — not only in approving their new science-and-technology measure but in advancing major legislation more broadly this year. With only faint majorities in Congress and the filibuster still intact, party leaders must walk a fine line on an amendment process that could easily scuttle even the most bipartisan of endeavors.

“I don’t see how we can pass it this week,” said Sen. Roger Wicker (Miss.), the top Republican on the Senate Commerce Committee. “If we don’t start having some meaningful amendments and actually practice regular order, I don’t see 60 votes for getting off the bill.”

The stakes are sure to be even higher for future debates, including infrastructure restructuring, as Democrats and Republicans maintain that they prefer to reach a compromise on improvements to the country’s roads, ports and pipes. Doing so probably will prove difficult, especially if both parties aren’t willing to stomach significant changes to their work once a package reaches the Senate floor.

For now, Democrats hope to approve their science-and-technology bill before departing at the end of the week. Schumer in recent days has sounded an ebullient note about its prospects, even as Senate Minority Leader Mitch McConnell (R-Ky.) on Monday again criticized its scope and urged Schumer against racing to advance it in a way that might close off additional avenues for GOP-led changes.

“We should not close debate on this bill until those amendments are addressed,” he said.

The bill centers on $120 billion in new spending, spread across the next five years, that aims to boost work at top science, space and research agencies. Schumer and his Republican co-sponsor, Sen. Todd C. Young (Ind.), say the funding could spur new advancements in quantum computing, artificial intelligence and the ultrafast wireless service known as 5G.

In doing so, lawmakers also see the investment as critical to prevent the United States from falling behind China, particularly in manufacturing the tools and devices that are critical to dominating these emerging tech fields. The Senate bill, in response, includes additional money to expand the country’s capability to produce technology such as semiconductors at a moment when the world is short on such chips, while helping to train a new generation of diverse scientists and researchers in these fields.

But the bill has experienced dramatic shifts — and seen some major additions — as Schumer, Young and a collection of top lawmakers shepherd it to the floor. Among the hundreds of pages tacked onto the proposal were provisions tied to shark fins, prohibitions about the government use of the social-networking app TikTok and a diplomatic boycott of the Olympics.