Now that Democrats control the House and Senate, they plan to revive earmarking — a process by which legislators can direct federal spending to their home districts. Democratic lawmakers are hoping earmarks can help solve two issues they’ll have in the new Congress: keeping their narrow majorities together on big votes, and boosting vulnerable members’ reelection chances when they face voters in 2022.

Earmarks have some heavy baggage. But as Democrats see it, the good outweighs the bad. Here’s what you need to know.

Brief history of earmarks

Earmarks are targeted spending projects that individual lawmakers insert into large spending bills without a direct vote, delivering something to the lawmaker’s district. For instance, a member of Congress from an urban district might ask for a larger space for the local Boys and Girls club; a member with a large research university might ask for a research grant; or a member with a harbor might ask to get it dredged so larger ships can dock there. These are possibly the purest form of “pork barrel” spending. And when running for reelection, members easily and often take credit for sending money to their districts.

Earmarks have been part of the federal budget since the first Congress in 1789, but they came to prominence in the 1990s when a bipartisan group of leaders on the powerful appropriations committees in the House and Senate streamlined the process by which members obtain them. Eventually they would codify the process by having members submit letters formally requesting their earmarks; some even created request forms.

Earmarks became a hot campaign issue in the early 2000s after a long string of scandals in which lawmakers from both parties secured earmarks not for the good of the community but to enrich themselves. Some accepted bribes from the community member benefiting from the earmark; others secured earmarks to improve property they owned. When Republicans took control of the House in 2011, they banned the practice. Urged by President Barack Obama, the Democratic Senate followed suit shortly afterward. Earmarks have been defunct since.

Why Democrats are bringing them back

However, earmarks are useful to congressional leaders as tools to keep the party together when Congress votes on important bills. When leaders identify wavering members, they can offer to insert an earmark that would send something to that member’s district to win them over.

Those wavering are typically the party’s moderates, often members from swing districts representing moderate constituencies. Moderates (and the voters they represent) always find a party’s legislative priorities to be more liberal or conservative than they’d prefer, and usually need some persuading to sign on. With the current Democratic majorities, this means senators such as Joe Manchin III (D-W.Va.) and Kyrsten Sinema (D-Ariz.) or representatives like Conor Lamb (D-Pa.) might need earmarks to go along with some big votes.

Moderate members can find it easier to vote for the party’s bill if the bill has something specifically for their voters. Members can then explain to voters that while the bill might not be perfect, the community wouldn’t receive these things if the bill didn’t pass.

A second reason Democratic leaders want earmarks is to help vulnerable members win reelection. Vulnerable majority-party members get a disproportionate share of earmarks, which they can point to when running for reelection. This spending helps members win, especially Democrats. Majority-party leaders can make sure only their party benefits — vulnerable minority-party members don’t get earmarks.

Broader benefits of earmarks

Earmarks may also benefit the broader political system, though that’s probably not on Democrats’ minds. Even though earmarks have been dormant for a decade, targeted spending is not. The government still approves many spending projects, just through different means. Currently, bureaucrats hold much of the authority to decide which local projects the government will fund.

These bureaucrats sometimes approve projects at the request of Congress members, which makes is substantively equivalent to earmarking. Other times, bureaucrats make decisions on their own, removing electoral accountability for the decision.

Defenders of earmarks point to two benefits of limiting bureaucrats’ influence over directed spending. First, earmarks that have a lawmaker’s name affixed provide greater public accountability. Voters have a chance to register approval or disapproval when the officeholder runs for reelection.

Second, earmarks help Congress protect its interests in the U.S. separation of powers system. Constitutionally, Congress holds the power of the purse; bureaucratic decision-making allows the executive branch to encroach on that authority. Bringing back earmarks empowers Congress.

Earmarks aren’t perfect

Earmarks come with their own set of problems. Because earmarks make it so easy for a single member of Congress to direct government money to an individual recipient, unscrupulous members have plenty of opportunities to use them to enrich themselves or their buddies.

Several earmarks-related scandals erupted the last time Congress used them prominently. Most notably, Randy Cunningham (R-Calif.) went to jail for taking bribes in exchange for earmarks. John Murtha (D-Pa.) set up a complicated pay-to-play scheme involving earmarks and probably would have gone to jail, too, but he died while under federal investigation.

That said, while such sensational stories get a lot of attention, they emerge from only a tiny fraction of earmarks. The vast majority are small projects that benefit local communities. A few can have bigger impact — NASA’s New Horizons project, which in 2015 famously sent scientists and the public the first new images of Pluto in decades, was saved from cancellation a decade earlier by an earmark from former senator Barbara A. Mikulski (D-Md.).

Democrats promise that they have changed earmarks to avoid misuse, including banning private corporations from receiving earmarks. Democrats are betting that the new earmarks will both improve their ability to hold the party together on legislation and boost party members’ reelection chances.

Jeffrey Lazarus (@jlazarus001) is a professor of political science at Georgia State University. He is co-author of “Gendered Vulnerability: How Women Work Harder to Stay in Office” (University of Michigan Press, 2018).