Just days after Democratic Gov. Janet Mills announced her campaign for the U.S. Senate, she unwittingly appeared in an ad expressing appreciation for the person she hopes to unseat next November, Republican Sen. Susan Collins.
The ad, broadcast on local TV stations and digital platforms, was part of a $1 million “issue advocacy” campaign by the group One Nation and designed to cast Collins as a senator with the clout to deliver for Maine. The nonprofit spends millions of dollars promoting Senate Republicans who are “delivering President Trump’s agenda.” It’s not required to disclose its donors.
Senate Democrats have their own dark money counterpart, Majority Forward, which has been running ads against Collins for the past several months.
One Nation and Majority Forward combined to spend an estimated $259 million on a handful of key Senate races last year, according to an analysis by the Brennan Center for Justice, a nonpartisan organization. Both are among a constellation of deep-pocketed outside groups hoping to shape the debate and outcome of a 2026 Maine U.S. Senate race that could determine which party controls the chamber after the midterm elections.
AdImpact, an organization tracking political ads, estimates the Maine Senate contest could help draw more than $300 million in spending on congressional races in the state next year. That’s nearly a third more than the record-smashing amount spent in 2020 when Collins secured her fifth term.
In that race, Republicans and Democrats used an array of political organizations to try and influence how Mainers voted. Some groups were party committees like the Democratic Senatorial Campaign Committee (DSCC) or the National Republican Senatorial Committee (NRSC), which spent $272 million and $301 million nationwide, respectively, in 2024.
The NRSC and DSCC have to disclose donations and spending. So do super political action committees, or super PACs, that operate under similar rules but can take and spend unlimited cash on ads and other persuasion methods. Other groups were dark money organizations like One Nation and Majority Forward, nonprofits that don’t have to reveal their funding sources and often direct that secret cash directly to super PAC affiliates — all while using separate influence campaigns that are increasingly difficult to track and quantify.
In some cases, the super PACs and dark money groups exploited vague and rarely enforced rules to effectively act as extensions of party committees like the NRSC and DSCC to operate as “shadow parties,” according to the Brennan Center for Justice.
One Nation and Majority Forward are part of that apparatus, often funneling cash to affiliate super PACs run by the same staff and connected to Senate leaders.
Based on the early spending patterns, the 2026 contest is poised to take a similar tack. That means Maine voters will be inundated with ads, but receive limited information about who is paying for them and what those benefactors might want if their preferred candidate and political party wins.
Several studies suggest that the multimillion dollar ad wars have little to no effect on election outcomes, but Sanford University political science professor Adam Bonica recently argued that politicians are still convinced otherwise, “a self-fulfilling prophecy, creating a vicious cycle where the perceived need for big money gives billionaires outsized influence over the entire system.”
At the same time, political organizations are increasingly using methods to shield that influence from public view. Dark money spending on elections climbed to $1.9 billion last year, according to the Brennan Center for Justice analysis.
Maine Public has compiled an early guide to the groups poised or already spending on the 2026 contest. Some are dark money groups. Others are super PACs. Some of the super PACs draw from dark money sources.
This is not an exhaustive list. It will likely grow. We’ll post updates as we’ll learn more along the way.
GOP groups
Senate Leadership Fund (super PAC)
This super PAC is consistently one of the top outside spending groups in the country, ranking No. 5 in 2024, according to data compiled by OpenSecrets, which tracks campaign spending. It spent $12.6 million in the Maine Senate race in 2020, ranking third among all outside groups. While the group operates separately from the NRSC, it’s connected to GOP Senate leadership. This group, along with the Senate Majority PAC, its Democratic counterpart, is described by the Brennan Center for Justice as a shadow party super PAC, allowing it to raise unlimited funds from corporations, individuals and nonprofits. Unlike the NRSC, which supports all Republican senatorial candidates, the Senate Leadership Fund mostly focuses on the most competitive races. It spent $211 million during the 2024 election and $293 million in 2020.
One Nation (nonprofit, dark money)
This group is considered the dark money affiliate of the Senate Leadership Fund. The group can spend directly on electioneering communications such as TV ads, but it’s also a direct contributor to the Senate Leadership Fund and often targets the same races. It funneled $10 million to SLF in 2024 and was the largest donor during the 2020 cycle at $85 million. One Nation has already invested in the Maine Senate race and has been running ads designed to bolster Collins’ influence in the Senate and money secured for Maine. Unlike a super PAC, it doesn’t have to disclose donors.
Pine Tree Results (super PAC)
This new super PAC has raised $5.6 million so far and has a similar donor profile as the now-defunct 1820 PAC, which spent $11.8 million on the 2020 Senate race to boost Collins, ranking No. 4 among all outside spending organizations. Its donors include Blackstone CEO Stephen Schwarzman, CEO of Elliott Management Corporation Paul Singer and the CEO of Palantir Alex Karp. (Palantir was founded by Peter Thiel and has secured millions in federal contracts under the Trump administration — $128 million in September alone, according to USAspending.gov. Its software is now helping ICE track and deport undocumented immigrants.) Schwarzman and Singer were among the lead funders of 1820 PAC, which also included multibillionaire and Oracle founder Larry Ellison. Ellison briefly eclipsed Elon Musk as the world’s richest person this fall. He’s building a media empire via his son David, who owns Paramount Skydance, which recently acquired Paramount Global — the parent company of CBS News. The Pine Tree Results PAC has not yet spent on the Senate race.
Stronger America (nonprofit, dark money)
This nonprofit has reportedly already run more than $2 million in ads boosting Collins. Its sources of revenue are shielded by its nonprofit status. It’s a relatively new issue advocacy organization.
Stronger Maine (super PAC)
This new super PAC ran at least $475,000 in ads in October defending Collins’ votes during the recent government shutdown. Individual donors to the PAC will eventually be disclosed, but it registered with FEC between reporting periods — and during the government shutdown — so that information is not yet public. The PAC could be linked to Stronger America (see above). Tax and filings for Stronger America and FEC filings for Stronger Maine show the groups share the same treasurer.
Democratic groups
Senate Majority PAC (super PAC)
The Democratic counterpart to the GOP’s Senate Leadership Fund and one of the biggest spenders on electioneering, dropping more than $311 million during last year’s election. It spent nearly $270 million in 2020, including nearly $28 million on the Maine Senate race, making it the top spending among outside groups in that contest. The PAC is affiliated with Senate minority leader Chuck Schumer. It will have a heavy presence in Maine in 2026, although its affiliates will likely assist. SMP contributions are public because of its PAC designation and it has received donations from labor unions and corporations. However, the window into its finances is limited because much of its money comes from the treasuries of dark money nonprofits that don’t have to disclose donors. In 2020, SMP’s top contributor was Majority Forward, an affiliated nonprofit that gave $53 million.
Majority Forward (nonprofit, dark money)
This nonprofit has already spent money on the Maine U.S. Senate with “issue ads” targeting Collins. Like One Nation, tracking Majority Forward’s spending to influence races is difficult because disclosure rules set by the IRS are different from the FEC guidelines for super PACs. However, the Wesleyan Media Project estimated that Majority Forward was among the biggest spenders during the 2020 election. While a lot of that spending was on ads, it also funneled $60 million to affiliated PACs, including the Senate Majority PAC, which then spent money expressly opposing Republican candidates, including Collins. Majority Forward does not have to disclose its donors, but tax filings show it has received funding from several other nonprofits that also don’t have to reveal donors. In 2020, tax filings show that the Sixteen Thirty Fund nonprofit contributed $3 million to Majority Forward. More on the Sixteen Thirty Fund below.
Unrig Our Economy (nonprofit, dark money)
This nonprofit is the result of a merger between Tax March and Health Care Voter. The two groups were beneficiaries of grants from the Sixteen Thirty Fund, the left-wing advocacy giant that spent more than $300 million during the 2024 elections and more than $400 million in 2020, including the Maine U.S. Senate race. Sixteen Thirty Fund is an incubator for liberal advocacy groups and its nonprofit status allows it to shield the identity of its donors. However, past donors have included the nonprofit led by Swiss billionaire Hansjörg Wyss as well as the philanthropic network founded by George Soros. Its most recent tax filings show its $282 million in revenues last year were driven by individuals who gave $1 million or more. More than 60% came from five individuals who gave $10 million or more. Unrig appears to be operating on a much smaller budget, but it has recently run digital and television ads attacking Collins for not backing the extension of health care subsidies during the federal government shutdown. It’s unclear whether the group will be a big spender in 2026 or one of several groups affiliated with the Sixteen Thirty Fund seeking to tilt the Maine Senate race toward Democrats.
Women Vote! (super PAC)
An affiliate of EMILY’s List, an organization that supports pro-abortion Democratic women running for state and federal office. It has already endorsed Gov. Janet Mills’ candidacy. Women Vote! spent $4.3 million on the Maine Senate race in 2020, receiving financial support from EMILY’s List ($7.5 million) and Paloma Partners ($4.1 million), an investment firm founded by Democratic megadonor Donald Sussman, who briefly owned the Portland Herald from 2012 to 2015. In 2024, Women Vote! Spent $26 million trying to boost Democratic candidates and its financial backing received a boost from the Senate Majority PAC ($5.9 million) and Future Forward USA ($5.2 million). Future Forward USA was the top outside spending group in 2024, dumping $509 million on federal races, according to an analysis by Open Secrets.
This edition of Maine's Political Pulse was written by State House bureau chief Steve Mistler and produced by news editor Andrew Catalina. Read past editions or listen to the Political Pulse podcast at mainepublic.org/pulse.
