This year’s primaries will be the most expensive on record
What fifteen years of inflation-adjusted campaign spending data tells us about politics in 2026
In the 2026 Democratic primary for U.S. Senate in Michigan, Representative Haley Stevens reportedly benefited from over $60 million in spending from outside groups. This enormous price tag has been reported as possibly the most expensive Democratic primary in history, possibly surpassed only by the Texas Senate race earlier this year.
But as friend of the site Nathaniel Rakich has frequently pointed out, while in raw dollars these numbers are eye-popping, most election finance trackers don’t adjust for inflation. This makes it hard to know whether spending in 2026 really is at an all-time high. So today, we’re looking at outside spending in every primary season since 2010 (when the Citizens United decision opened the floodgates to unlimited outside spending in federal elections), adjusted to June 2026 dollars, to see how things have changed over time. Is 2026 shaping up to be the most expensive election year on record?
To do this, we’re relying on data from OpenSecrets on outside spending in Federal primary races. OpenSecrets tracks every race where the total outside expenditures exceed $1,000; we’ve inflation-adjusted this from 2010 dollars to look at every partisan primary for House or Senate with at least $1,540 in outside spending in June 2026 dollars. (From here on out, all dollar figures should be read as inflation-adjusted to June 2026.)
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Outside actors are spending more money in more races
The first thing we noticed in the data is the dramatic increase in the number of races where outside groups have spent enough money that they show up in OpenSecrets’ data. In 2010, just 112 partisan primaries saw more than $1,540 in outside spending. While growth hasn’t always been steady, the number of primaries in which outside groups are spending money has slowly grown over time; by 2024, the number of races in which outside groups spent more than $1,540 had more than doubled to 241. This growth has been almost entirely in House primaries, where prior to 2018, typically fewer than 100 races saw significant outside spending, but ever since have had over 175 primaries with outside spending each cycle.
This growth is particularly high in Republican primaries. While outside spending has been growing among both parties, in every single cycle, the number of Republican primaries with more than $1,540 in outside spending exceeded the number of Democratic races, sometimes by more than 2-to-1.
The amounts outside groups are spending are increasing, too. If we consider the 50 most expensive House races in each cycle, for example, the average amount spent by outside groups has steadily grown, from less than $200,000 in 2010 to over $3.7 million in 2024. In 2010, just one House race saw more than $1 million in outside spending; in 2022 and 2024, only three of the 50 most expensive House primaries had less than $1 million in outside spending, and both cycles had three races where outside groups spent over $10 million.
Republicans are spending more and more in high-stakes Senate primaries
In 2014, incumbent Mississippi Republican Thad Cochran faced a Tea Party challenger, then-State Senator Chris McDaniel. McDaniel was endorsed by typical Tea Party actors, like Club for Growth and the Senate Conservatives Fund. In the previous cycle, a Tea Party nominee had knocked off an incumbent Republican in Indiana, only to go on to lose in November, so the GOP was taking no chances. In the 2012 Indiana primary, outside spending totaled just shy of $6.5 million. Spending more than doubled to over $13 million in the Mississippi race.
Cochran went on to defeat McDaniel in a runoff by just two percentage points. And since then, GOP spending in races with potentially problematic primary challengers has continued to grow. In 2016, nearly $16 million was spent in the New Hampshire primary where incumbent Kelly Ayotte faced a challenge from her right from former state senator Jim Rubens. In 2018, over $17 million was spent by outside groups in Wisconsin, where then-State Senator Leah Vukmir was locked in a tight race with Tea Party conservative Kevin Nicholson. In 2020, almost $18 million was spent in a close contest between incumbent Senator Roger Marshall and controversial former Kansas secretary of state Kris Kobach.
In each of these cases, the establishment candidate went on to win their race. And in 2022, when a number of races saw less mainstream candidates challenging the incumbent, outside GOP spending exploded. Seven Republican primary contests for U.S. Senate in 2022 saw more than $18 million in spending: Ohio, Pennsylvania, Missouri, Alabama, Wisconsin, North Carolina, and Arizona. These 7 contests are among the 8 Senate primaries with the most outside spending since Citizens United. (The other one is the Ohio Republican primary in 2024, in 5th place.) On average in these 7 races, outside groups spent $29,162,201 in the Republican primary. The most expensive primary of all was the 2022 Ohio Senate contest, a tight 3-way contest between now-Vice President JD Vance, then-State Senator Matt Dolan, and former Ohio treasurer Josh Mandel.
Republican groups also typically shell out more in, and in more, Senate races than Democrats. In every cycle since Citizens United other than 2020, there are more GOP races in the top 20 most expensive primaries than Democratic races (in 2020, there are 10 of each). (See the table at the end of the article for a full list of primaries and their inflation-adjusted outside spending.)
Spending in nonpartisan primaries has also grown
In nonpartisan primaries, where all candidates run on the same ballot regardless of party, outside spending has also grown in the years since Citizens United. Because only four states use a nonpartisan primary system (and in 2010, only one state did – Washington), there are fewer of these races each cycle, but more and more are seeing outside groups spending to promote candidates.
On the Senate side, there are very few nonpartisan primaries to consider. Only three have ever topped $1 million: Alaska in 2022, Louisiana in 2014, and California in 2024. Just one of these races topped $20 million: the open primary to succeed Laphonza Butler in California in 2024, which cost outside groups nearly $23 million.
With over $60 million in outside spending, Michigan’s Democratic Senate primary now indeed appears to far and away top the list of most expensive primaries in history. Due to the premium Republicans place on their primary elections, Texas’ Republican Senate primary also will likely land near the top — once all the final reporting is made this year.
When the dust settles at the end of the primary cycle, and all the FEC reports are finalized, we’ll find out for sure if 2026 continues the trend of increased spending across the board, or if just a few high-profile races drove enormous dollars.
For now, what we can definitely say is that, even if you adjust for inflation, elections are getting more and more expensive every year.
Want even more? Here’s the complete data we used for this article, for you to play with yourself.
Methodology
Primary expenditures by outside groups were gathered from data published by OpenSecrets. For partisan races, spending conducted either for or against Republicans was counted as spending in the Republican primary, and spending conducted either for or against Democrats was counted as spending in the Democratic primary. For nonpartisan races, all spending was included.
Inflation adjustments were made using the Bureau of Labor Statistics CPI Inflation Calculator. Each race was adjusted to June 2026 dollars1 based on the month in which the primary was held. Election dates were drawn from the Federal Election Commission.
The earliest dates of primaries in this dataset were in March 2010. In June 2026 dollars, $1,000 in March 2010 would be worth $1,534.49. We thus used $1,534.49 in inflation-adjusted dollars as the minimum for a race to appear in the dataset, to ensure comparable data over cycles.
Footnotes
The actual inflation-adjusted value is $1534.49. We’ve replaced this with $1540 to make things easier to read, and also because none of the races under consideration had spending between $1534.49 and $1540, so it makes no difference.