One of the most vulnerable Republican 2020 Senate incumbents is getting major air cover from a new super PAC designed to sound like a local group. But all signs point toward the involvement of the country’s biggest business lobby 500 miles away in Washington, D.C.

The group, a super PAC called 1820 PAC, has dropped about $700,000 on ads this year pressing for the re-election of Sen. Susan Collins (R-ME), who is facing a tough fight in a race sure to be one of the most expensive of the cycle. The name of the PAC is a reference to the year of Maine’s founding, but 1820’s mailing address is in Washington. And a PAY DIRT analysis of public records shows the fingerprints of one of DC’s heaviest political hitters: the U.S. Chamber of Commerce.

The Chamber didn’t respond to our comment request. But when asked about its relationship with 1820, Scott Reed, a senior political strategist for the business group, told us in an email, “The Chamber’s voter-education program is in close contact with other outside groups that share the same goals.”