Democrats are eager to depose not just President Trump, but his congressional enablers and defenders, too. And they’re opening their wallets to prove it. In Kentucky, Amy McGrath, the retired fighter pilot who hopes to challenge Senate Majority Leader Mitch McConnell, has raised $16.9 million. Last quarter, Democrats sent $3.5 million to South Carolina to Jaime Harrison, who is challenging Sen. Lindsey O. Graham.

But McGrath, Harrison and several others like them face a problem: They’re probably going to lose. Meanwhile, the candidates challenging less famous, workaday Republicans are struggling to find donors — and many of them are in states or districts that could actually flip. This dynamic is a classic case of pragmatism versus passion in an era when party leaders are losing control of contributions and rank-and-file donors are increasingly inclined to go their own way. But liberal pockets are not bottomless. In a zero-sum competition for cash, the search for brand-name scalps the Democrats may never claim could keep Democrats from winning the seats, and the Senate majority, that is truly within reach.

To put the situation in context, Democrats need to pick up three seats to take control of the Senate (currently 53-47), assuming that none of their incumbents lose. But since Democrats will likely lose Sen. Doug Jones’s seat in Alabama, they must win four seats if a Democrat wins the presidency (with the vice president serving as a tiebreaker) and five if voters reelect Trump.

Forecasters say the most vulnerable Republicans incumbents are Sens. Cory Gardner in Colorado, Susan Collins in Maine, Thom Tillis in North Carolina, Martha McSally in Arizona and Joni Ernst Iowa. According to the Center for Responsive Politics, three of the likely Democratic candidates have raised less than half of their opponents’ haul in the last reporting period. Some of those Democrats have also spent considerable funds trying to win primaries or gain some early name recognition. For example, the Democratic nominee in North Carolina, Cal Cunningham, spent more than $3 million during the primary period and is left only with $1.5 million in cash-on-hand compared to the incumbent, Tillis, who has $5.4 million in his bank account.

Previously, a pragmatic party would use its money as efficiently as possible by amassing resources in winnable seats. But small donors have become a crucial force within the party. They can be a boon to the nation’s politics, which continues to rely on megadonors to finance big races, but the way they make decisions — following their policy and personality preferences without regard to overall majority — can undermine their potential power.

Small donors tend to be catalyzed by media events, which motivate them to make in-the-moment donations over the Internet. When Rep. Joe Wilson (R-SC) screamed “you lie” at President Obama during a 2009 address to Congress, Wilson netted $2.7 million with the campaign claiming more than 50,000 donors within weeks. In the same way, when Republican Rep. Elise Stefanik defended Trump during his impeachment hearings, her Democratic opponent raised $1 million that weekend, even though the Cook Political Report rates her race as “Safe Republican.”

But small donors are also motivated by what political scientists call “affective partisanship” or an intense dislike of the other party, particularly its leadership. The fact that Democrats loathe McConnell is probably why McGrath is the second-highest Democratic fundraiser running for Congress and received almost two-thirds of her $16.9 million from small donors. To be sure, McConnell’s favorability rating among the national electorate is very low (a recent Economist/YouGov poll puts him at 36%). Similarly, a Morning Consult survey showed he is the second least popular senator among constituents in his home state. But Republican voters like his defense of the president during the Senate impeachment trial. Keep in mind, Kentucky voted 63% Republican and 33% Democrat, a gap of 30 points. Graham’s challenger, Jaime Harrison, has the next best haul and received 58% of his war chest from small donors. Graham was also electorally savvy in being a fierce guardian of the president in a state that voted 55% for Trump compared to 41% for Clinton, a gap of just over 14 points. To be sure, a Democratic wave election might give these candidates a chance, but few analysts are predicting a wave in 2020 as was observed in 2018 for Democrats in the House.

Conversely, almost none of the candidates in the competitive races come close to getting as many small donors as McGrath or Harrison. Most are lucky to get one-fifth of their funds from them. In North Carolina, where the Democrats lost the presidential contest by just 4 points, the Republican incumbent Tillis has raised $9.9 million and the Democratic challenger took in $4.5 million, with just 19% coming from small donors. In Colorado, where Clinton won by 3 points, the Republican incumbent, Gardner, has raised $10.9 million compared to the likely nominee and former popular governor, John Hickenlooper, who has raised $4.9 million, with 20% from small donors. In Iowa, the Democrats lost the presidential contest by just under 10 points but party registration is roughly even between Republicans and Democratic voters. The incumbent Ernst has raised $8.1 million compared to the likely Democratic challenger, Theresa Greenfield, who as raised just $3.3 million, with just 21% from small donors. Finally, in Maine the Democratic challenger Sara Gideon is slightly ahead or neck-and-neck in recent polls against the Republican incumbent Collins. But her fundraising lags Collins, and worse, she has much less cash-on-hand at this point, with Collins having $7.2 million to her $2.8 million. Due to Collins pivotal role in voting against impeachment Gideon has reaped some rewards by small donors, getting 40% of her funds from them. That is still considerably less attention than for the contests in Kentucky and South Carolina.

The exception is Arizona Democrat Mark Kelly, a retired astronaut and husband of former Rep. Gabrielle Giffords who resigned from Congress after being shot in the head at an event in 2011. Despite never having run for office, Kelly’s celebrity status helps make him the single largest fundraiser in Congress this year, drawing in an astounding $20.1 million, with almost half that amount from small donors. He is likely to win a state trending Democrat that Trump won by just four points. The polls since August have put him consistently ahead of the Republican incumbent McSally, by an average of 4 points.

These dynamics illustrate the promise and potential perils of relying on small donors to help parties compete. On the positive side, it could mean that candidates do not have to rely as much on superwealthy donors to finance their campaigns. The shift could plausibly improve political representation in some ways. And why shouldn’t passionate donors put the heat on people like McConnell and Graham to hold them accountable for positions they find objectionable? Finally, there are plausible long-term benefits of contesting long shot races, because it can lead to sincere efforts to woo voters who often get ignored, as was the case in 2018 when then-Rep. Beto O’Rourke got within striking distance of Sen. Ted Cruz in Texas’s senate race and gets some credit for boosting Democratic House candidates with his statewide turnout efforts and giving some life to the Texas Democratic Party.

But small-donor impulses also mean that the party may “waste” money on lost causes. Political parties tend to invest in candidates who have the biggest potential for wins, while individual donors (especially small donors) prefer candidates who share their preferences. And these preferences tend to be extreme relative to those of voters, making it harder for small donor-funded candidates to win general elections with swing voters.

Ironically, though, even as many Democrats talk about the 2020 elections in apocalyptic terms, small donors don’t seem to support the most competitive Senate candidates who could blunt the impact of a potential Trump reelection. That unwillingness makes the party even more reliant on the megadonors who finance Super PACs. In this way, Super PACs become the tool of choice for the party and its candidates and could, therefore, increase the very influence of unlimited money many small donors detest.