Federal agents had amassed enough evidence to pursue a sweeping corruption case against Senator Susan Collins by late 2024, documents and emails reviewed by ProPublica show. The probe focused on allegations that Collins helped steer nearly $40 million in naval contracts to Navatek, a boat-building firm, in exchange for a $150,000 contribution funneled through a shell company to a pro-Collins super PAC. The investigation was shut down in 2025 after Donald Trump returned to office and depleted the FBI anti-corruption unit and the DOJ's Public Integrity Section through firings and policy changes.

Collins and her staff have called the bribery allegations outlandish and categorically false, noting that the primary source is Martin Kao, a convicted felon sentenced to prison in 2025 for wire fraud and money laundering. A spokesperson for the senator stated that the FBI and the Justice Department under the Biden administration had previously investigated the matter and concluded no wrongdoing occurred. Republican allies, including Senator John Thune, described the reporting as a political hit job designed to affect the upcoming election.