Polling Average
80%60%40%20%0%
55.9%
29.7%
Maine Democratic Senate nominee?
$6.1M
JUN 10, 2026Primary Election
Party selects its nominee.
Overview
Current roleGovernment official/administrator
PartyDemocratic
Political ideologyProgressive Democrat
LocationMaine
BackgroundGovernment official/administrator
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EducationOld Town High School (graduate)
Notable personal detailsDavid Allen Costello is a Democratic candidate for the U.S. Senate in Maine (Class II) in the 2026 cycle. He is a former Androscoggin County Charter Commission member and has worked in senior roles across state, local, and federal government, including environmental and climate-related positions. He is a graduate of George Washington University and the London School of Economics, and has lived in Brunswick, Maine.
SourcesShowHide
pressherald.comcostelloforsenate.comballotready.orgmainedems.orgballotwire.comtownofwhitefield.comwinthropmaine.govbrunswickme.govgopknoxcounty.comptindirectory.comthedailyelm.comwashingtonpost.comuselectionatlas.orgivoterguide.comfalmouthme.orgnasba.orgclerk.house.govlwvme.orgen.wikipedia.orglinkedin.commainemorningstar.comwmtw.comontheissues.orgdemocracyinaction.usfec.govpoliticspa.commainepublic.orgfacebook.comnpr.orgballotpedia.orgthreads.cominstagram.comvotesmart.orgorganizations.ballotready.orgsupport.ballotready.orghistory.house.gov
Positions
LiberalConservative
Economy & Taxes
Supports increasing taxes on wealthy individuals and corporations, expanding tax credits and incentives for low- and middle-income people and small businesses, and using tax changes to fund expanded government programs and investments (infrastructure, R&D, housing, Social Security/Medicare protection). Advocates a global minimum corporate tax and reallocating subsidies from large agribusiness and fossil fuels to rural and clean-energy initiatives.
Healthcare
Supports expanding access to government-provided coverage by offering Medicare (including dental and vision) to anyone who wants it, improving the Affordable Care Act for those who do not enroll in Medicare, and increasing funding for substance use and mental health services.
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Immigration & Border
Supports comprehensive immigration reform that secures borders while facilitating legal immigration and addressing worker shortages; emphasizes enactment of reforms to expand legal pathways alongside border security measures.
Abortion & Reproductive Rights
Supports protecting women’s reproductive rights, including codifying Roe v. Wade and increasing funding for organizations like Planned Parenthood. Backs actions to protect reproductive health decisions and broader civil rights protections.
Climate & Energy
Supports an aggressive, science-based national climate action plan with strict greenhouse gas emissions caps, large clean energy and efficiency investments, GHG sequestration goals, and reallocation of fossil-fuel subsidies toward clean energy. Backs policies such as a carbon tax and expanded renewable development (wind, solar, hydro) while urging protections for affected communities and fisheries.
Public Safety & Guns
The candidate supports stronger federal gun safety laws including universal background checks, safe storage requirements, bans on military-style/assault weapons, red flag measures, and increased funding for mental health and community policing; he also supports stricter sentencing for gun-related crimes while saying he would not deny responsible citizens the right to own guns.
News
AINews Summary
Last updatedMay 3, 2026
David Costello is in the mix in Maine’s contested Democratic U.S. Senate primary, running against Gov. Janet Mills and Graham Platner. Recent coverage has centered on Platner, including a Republican-aligned PAC spending nearly $2 million on attack ads highlighting a tattoo with Nazi imagery that Platner has covered up and a past social media post about sexual assault. A new poll also shows Platner as the primary frontrunner, with Mills and Platner leading Sen. Susan Collins in hypothetical general-election matchups.
pressherald.com+35
Polls
Maine Democratic Senate nominee?
Aggregation source: FiftyPlusOne
Endorsements
Maine Democratic Senate nominee?
Endorsers of David Allen Costello for Maine Democratic Senate nominee?
Gov. Janet Mills
Public endorsement
Gov. Janet Mills endorsed David Costello in Maine's U.S. Senate race.
Fundraising
Latest report: Cycle 2026Total raisedCash on hand
$143.5K
$107.6K
$71.7K
$35.9K
$0
2024
2026
LatestYear
Total raised
Cash on hand
Total spent
Burn rate
Cycle 2024
$111.3K
$0.00
$111.6K
$4.7K
Cycle 2026
$143.5K
$47.1K
$96.3K
$6.4K
Source: FEC