A previous version of this article misidentified the state affiliations of two U.S. House members. Rep. Peter A. DeFazio (D) is from Oregon, not Washington, and Rep. Katie Porter (D) is from California, not Oregon.

The return of congressional earmarks has sparked a massive dash for cash on Capitol Hill, where more than 300 House Democrats and Republicans have sought nearly $21 billion in federal funding to help their home districts and pet projects — and shore up their reelection prospects.

The sheer volume of the requests sets the stage for some difficult decision-making — and fierce behind-the-scenes haggling — on the part of House lawmakers who revived the once-maligned spending practice this year as a way to build political coalitions in an ever-divided Washington.

Every House Democrat except one has submitted an earmark request. In total, they have sought funding for nearly $14 billion in projects, while just over half of the chamber’s Republicans have appealed for a combined $7 billion, according to new congressional data analyzed by The Washington Post. The breakdown reflects the bipartisan appetite for federal aid, even as some in the GOP remain wary about resurrecting a process they helped to dismantle about a decade ago.

Many lawmakers’ new petitions for funding seek to fix crumbling roads, bridges and pipes in their political backyards, illustrating Democrats and Republicans’ shared interest in infrastructure as the debate continues around one of President Biden’s economic policy priorities.

Rep. Garret Graves (R), whose Louisiana district includes Baton Rouge, asked for more money than any other lawmaker: He sought roughly $1 billion in transportation-related earmarks, hoping to fix what he described in a statement as one of the worst highway bottlenecks in the country. Rep. Kim Schrier (D), meanwhile, submitted more than $900 million in requests to widen highways and repair bridges in her western Washington district.

The two lawmakers pursued the federal aid as part of the early House debate over a multiyear bill authorizing federal road, highway and transit spending led by Rep. Peter A. DeFazio (D-Ore.), chairman of the House’s top transportation committee. DeFazio has promised to parcel out aid equitably as he weighs a total of $14.8 billion in requests for what the panel calls member-designated projects.

The panel’s work marks one of two venues for earmarks this year: The House Appropriations Committee, chaired by Rep. Rosa L. DeLauro (D-Conn.), has received nearly $6 billion in petitions for community project funding as it begins its annual process to fund the government in the 2022 fiscal year.

Entering the funding fight, GOP Rep. Beth Van Duyne, who represents a portion of Dallas, petitioned House appropriators for more than $354 million in earmarks largely to finance massive improvements at the Dallas-Fort Worth International Airport. Rep. Karen Bass (D-Calif.), meanwhile, asked the panel for $1 million in new funding for a revitalization project in Crenshaw, a large and historic Black neighborhood in Los Angeles.

And multiple lawmakers aimed to steer government dollars toward local police and public-safety projects. Rep. Matthew Cartwright (D-Pa.), for example, requested $2.1 million to “improve our community policing efforts by purchasing new tasers and dash cameras,” which he said would improve accountability. House members submitted at least 97 requests totaling $104 million that mention police or policing, a Post analysis found.

Some ethics watchdogs said the majority of requests appeared at first glance to be legitimate, indicating that the House’s new, regimented rules may have prevented some of the clear missteps of the past. Congress banned earmarks in 2010 amid a dizzying array of controversies that saw federal dollars proposed or disbursed to fund indoor rainforests and bridges to nowhere — along with allegations of corruption that sent some lawmakers to prison.

“People went to jail. There was illegal activity. There was a well-known trough of businesses on K Street where firms were organized around scooping up these contracts to win projects, some deserving [and] some not,” said Sheila Krumholz, executive director of the Center for Responsive Politics.

This time around, she said, it’s already clear that “there is going to be a lot of people paying attention to whether this just becomes a free-for-all, like it arguably was in the past.”

But the volume of requests still has stoked fresh criticism from spending hawks, particularly in the months after Congress added trillions to the deficit in response to the coronavirus. Citizens Against Government Waste, a conservative-leaning group that opposes earmark spending, pointed this week to what it saw as a series of problematic proposals on both sides of the aisle — including one, for example, from Rep. Linda T. Sánchez (D-Calif.), who sought $300,000 to construct a dog park in her congressional district.

In response, Sanchez stressed the spending would “significantly benefit a community growing in population and already suffering from a lack of green space,” adding in a statement: “Local individuals who pay federal taxes should have a say in where their money is being spent.”

House leaders still must winnow down the requests — and shepherd key spending and transportation legislation to passage with the help of the Senate — before any projects are funded. The process historically is fraught with politics, as members of Congress try to trade project funding in exchange for favorable votes. The dealmaking is likely to be even more intense this year, given the extent of Biden’s legislative agenda — and the limits of Democrats’ narrow congressional majorities.

“It will make it much less likely we have government shutdowns,” predicted Cartwright, reflecting on the 16-day period during his first year in Congress when federal funding lapsed. “If you have members [who] have a stake in the spending package, they’re much less likely to pull a sophomore prank.”

Much like the House, the Senate similarly has opened its doors for earmarks this year. Democrats led by Sen. Patrick J. Leahy, the chamber’s top appropriator, announced his plans in April, though Republicans have sent mixed signals about the extent of their participation. In gathering last month to adopt their party’s rules, Republicans ultimately did not vote to lift a longtime ban on earmarks. Yet the conference’s regulations are not binding, meaning lawmakers can seek project funding anyway — something that some Senate Republicans already said they would do.

In the House, at least, the party’s leaders hardly have shied away from seeking earmarks. Rep. Steve Scalise (La.), the party’s minority whip, requested nearly $28 million in funds. And Rep. Elise Stefanik (N.Y.), who aspires to take the No. 3 spot in the party’s leadership ranks, asked for more than $117 million.

On the Democratic side, meanwhile, the only member who opted against filing for earmarks was Rep. Katie Porter (Calif.), who publicly has said the House is wrong to have revived a practice that has in the past facilitated corruption.