A Washington businessman at the center of an illegal fundraising probe donated $50,000 to Hillary Clinton's campaigns and lesser amounts to those of President Obama and Secretary of State John Kerry, according to an exhaustive report from a public interest group.

The Center for Public Integrity found that the former accounting firm of Jeffrey Thompson delivered $500,000 to federal candidates overall, with Clinton receiving the most.

The Center, quoting federal prosecutors calling Thompson's former firm an "assembly line for illegal campaign contributions," found that "Thompson and other donors who listed the accounting firm as their employer have given at least $514,350 to federal candidates and political action committees since the 2002 campaign" cycle.

"The biggest beneficiary of those funds was former Secretary of State Hillary Clinton, whose campaigns took in $50,400. Clinton's presidential campaign committee received $40,300 from employees at Thompson's firm in November 2007, when she attended an intimate fundraiser at the company's headquarters in downtown D.C., according to three people who were at the event," said the Center.

"Other recipients include President Barack Obama ($14,500 in the 2008 cycle), former Democratic presidential candidate and Secretary of State John Kerry ($20,000 in the 2004 cycle), former Republican presidential candidate Sen. John McCain ($13,800 in the 2008 cycle) and Senate Majority Leader Harry Reid ($9,600 in 2009)," they added.

Their full report is here.

Paul Bedard, The Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.