The 2026 midterms are on track to be the costliest in American history. AdImpact projects $11.6 billion in political ad spending, with Senate advertising alone reaching $3.4 billion. The roots of this arms race go back to the Supreme Court's 2010 Citizens United v. FEC decision. The Brennan Center found that outside spending in Senate races more than doubled, from $220 million in 2010 to $486 million in 2014. It also found that just 195 people and their spouses supplied nearly 60% of the more than $600 million in super PAC donations over those years.
Whether this is good or bad is a real debate. Critics argue that a small donor class has outsized influence, and that dark money reduces transparency and can create conflicts between donors and candidates. Defenders argue that political spending is protected speech and that ads inform voters. They also point out that money has not reliably produced victories. In Ohio in 2024, Sherrod Brown raised $96.5 million to Bernie Moreno's $14.8 million. However, Moreno won (also helped by $186.1 million in outside support). In Pennsylvania in 2022, Mehmet Oz loaned his campaign more than $21 million and still lost to John Fetterman.
The cases below have totals that vary by source: OpenSecrets counts candidate and outside spending, while AdImpact tracks advertising only. Please note that numbers for 2026 are ongoing estimates.
1. Georgia 2020-21: Perdue vs. Ossoff (~$515 million, final)
This is the most expensive Senate race on record, at about $515 million in total spending, per OpenSecrets. Candidates raised huge sums: Ossoff $107 million and Perdue $68 million. Outside money was lopsided toward Republicans in the runoff. As of December, $84.2 million had backed Perdue or opposed Ossoff, against $44.4 million for Ossoff or against Perdue. The GOP side relied on American Crossroads, the Senate Leadership Fund (SLF) and its Peachtree PAC, each spending more than $40 million. Democrats funneled money through Senate Majority PAC (SMP) vehicles, with Georgia Honor spending over $18 million and The Georgia Way over $12 million.
2. Texas 2026: Paxton vs. Talarico (~$432 million so far, in progress)
Texas is the 2026 record-setter. Through September, spending across the primary and general elections reached $432 million, and AdImpact projects $440 million by Election Day, more than double the state's prior record of about $210 million. The money is heavily Republican. Texas PAC, tied to Senate Majority Leader Thune, has spent $131 million, and Trump's MAGA Inc. added about $11 million. Paxton's own campaign barely advertised, spending just $465,000 on ads by mid-September. Talarico is the fundraising star. His campaign had spent just under $50 million on general-election ads by Sept. 17. Even so, NPR reports Paxton's side has spent roughly $175 million against $71 million on Talarico's.
3. Ohio 2024: Brown vs. Moreno ($421.5 million, final)
OpenSecrets puts this race at $421.5 million, though Wikipedia cites a higher $483.4 million figure. The Republican win was powered by outside groups. SLF spent about $70.6 million, and the pro-Moreno outside total was $186.1 million. Democratic-aligned groups such as WinSenate ran ads attacking Moreno, but Brown's own fundraising was the Democratic side's main engine.
4. Georgia 2020-21: Loeffler vs. Warnock (~$411 million, final)
OpenSecrets' latest figure is $411 million, up from nearly $363 million in an early-January tally. Candidate fundraising was massive: Warnock raised $103 million and Loeffler $64 million, including a $23 million loan from Loeffler herself. In the runoff, SLF was the top outside spender at $32.1 million. A group backing both Republicans was mainly funded by Loeffler's husband, NYSE chairman Jeffrey Sprecher.
5. Georgia 2022: Warnock vs. Walker (~$400 million, final)
OpenSecrets data put this race at about $400 million. Warnock dominated candidate money: he raised $150.5 million to Walker's $58.3 million. Before the runoff, SLF and the SMP-backed Georgia Honor each spent about $38.5 million. SLF drew on dark money, as its largest source of funds was One Nation, which gave $20.6 million (though it doesn't disclose who its donors are). In the four-week runoff, pro-Warnock TV spending reached $54 million against $25 million for Walker.
6. Maine 2026: Collins vs. Platner/Jackson (~$384 million projected, in progress)
AdImpact's projection for this race alone is $384 million. That is an advertising figure, and it dates from June. Republican-aligned groups lead: $99 million versus $44 million for Platner and Democratic allies at the time. The funding models contrast sharply. Nearly 100 billionaires and their spouses have given almost $10 million to Collins' network. Platner's campaign, by contrast, has been powered overwhelmingly by small donations, though he also has dark-money support from Majority Forward, the nonprofit arm of Senate Majority PAC.
Of particular note here is that Grant Platner (the Democratic nominee) withdrew from the race in July due to various personal controversies, including assault accusations. Troy Jackson was chosen to replace Platner on the ballot. However, the fundraising reporting deadlines and estimates we do have are only from Platner's time as nominee. So it's yet to be seen if Jackson has continued the previous Democratic fundraising pace during Q3 of 2026 and into the final stretches of the campaign.
7. Pennsylvania 2022: Fetterman vs. Oz (~$372 million, final)
This race cost about $372 million. Oz's self-funding (over $21 million in loans) offset Fetterman's fundraising edge, since Fetterman raised nearly $4 for every dollar Oz did. Party super PACs anchored both sides: SLF pledged about $34 million, and SMP launched a $32 million campaign. By October, roughly 100 outside groups had spent more than $145 million.
8. Pennsylvania 2024: Casey vs. McCormick ($334 million, final)
OpenSecrets figures show a $334 million race, the nation's second-most expensive Senate contest that year. Through September, outside groups spent $108.3 million for McCormick or against Casey, versus $65 million on Casey's side. McCormick had his own super PAC, Keystone Renewal, bankrolled by billionaires including Ken Griffin ($10 million) and Paul Singer ($2 million). On the Democratic side, WinSenate, funded by Senate Majority PAC, spent $39 million.
9. North Carolina 2020: Tillis vs. Cunningham (~$296 million, final)
Spending totaled $295.8 million, with outside groups accounting for $219.7 million, split $119.5 million Democratic and $100.2 million Republican. Top Republican spenders were SLF ($47.2 million), American Crossroads ($23.8 million), and Americans for Prosperity Action ($12.2 million). On the Democratic side, Senate Majority PAC spent $35.8 million. The candidates themselves accounted for only about a quarter of the total.
10. Michigan 2026: Rogers vs. El-Sayed ($205 million+ disclosed so far, in progress)
Michigan is on pace to be the most expensive election in the state's history, with more than $205 million in disclosed spending. Undisclosed dark money will likely push the total higher. About $157 million is outside spending, roughly $75 million of it in the Democratic primary. In that primary, AIPAC and affiliated groups spent close to $30 million for Haley Stevens, their largest investment ever in one race, and El-Sayed won anyway. On the Republican side, SLF pledged $45 million to support Mike Rogers.
