If you judged by the more than 16,400 comments posted on a federal government website, you'd think there was a groundswell of older Americans demanding that federal officials hike payments to their Medicare Advantage health insurance plans.

Yet about 82% of the comments are identical to a letter that appeared on the website of a secretive advocacy group called Medicare Advantage Majority, a data analysis by KFF Health News has found.

The "dark money" group does not reveal its funders or much else -- other than to say it is "dedicated to protecting and strengthening Medicare Advantage" and is "powered by hundreds of thousands of local advocates nationwide."

"Our campaign provides information and offers tools for concerned Americans to use to reach decision makers," spokesperson Darren Grubb said in an email. The group has spent more than $3.1 million on hundreds of Facebook ads since September 2024, according to Facebook's Ad Library, a database of the social media company's online ads.

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