FIRST ON FOX: One of the most vulnerable Democratic incumbents in the U.S. Senate, who has a history of railing against the influence of lobbying in Washington, ranks as one of the most active senators when it comes to lobbyists entering and exiting his office.

Ohio Sen. Sherrod Brown ranks in the top-15 all time on Legistorm’s revolving door rankings that tracks congressional staffers who enter offices as lobbyists or leave offices to become lobbyists.

According to Legistorm, 64 individuals have lobbied before or after working for Brown’s office, which ranks him tied for #15 all time. 

Brown ranks #7 when it comes to senators who are actively serving in Congress.

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Sherrod Brown

Sen. Sherrod Brown, a Democrat from Ohio and chairman of the Senate Banking, Housing and Urban Affairs Committee, during a hearing in Washington, D.C., on June 22, 2023. (Nathan Howard/Bloomberg via Getty Images)

Staffers who previously worked for Brown are now lobbying for companies that include TikTok, Planned Parenthood, Exxon Mobil and Kroger.

Brown, chairman of the Senate Banking, Housing and Urban Affairs Committee, has hired at least 3 former lobbyists to serve as his chief of staff, Fox News Digital previously reported, including James Heimbach, who was once referred to as "hot commodity" in the lobbying world. After leaving Brown’s office, Heimbach continued lobbying including time with Bank of America, one of the country’s largest financial institutions.

Heimbach also lobbied for the Cigna Corporation, a company sued by Ohio for allegedly driving up the costs of prescription drugs by charging high fees for pharmacy benefit management services.

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Sherrod Brown rail safety rally

US Senator Sherrod Brown, a Democrat from Ohio, during a rail safety event in Columbus, Ohio, US, on Wednesday, April 12, 2023.  (Maddie McGarvey/Bloomberg via Getty Images)

Brown has a long history of lamenting the influence of lobbyists in politics as he frames himself as a populist Democrat in Ohio, a state Trump won by 8 points in 2020.

"Something's wrong with corporate America, and something's wrong with Congress and administrations listening too much to corporate lobbyists," he told the Rolling Stone last year.

Brown has also claimed he "took on corporate lobbyists" to get the Inflation Reduction Act passed and often talks about how he has "fought" lobbyists throughout his career.

"Sherrod has always stood up to special interests to level the playing field for Ohioans," Brown’s website states. "Whether it’s Big Pharma, Big Oil, or Big Banks, Sherrod is fighting back against the Wall Street, profit-at-all-costs business model to make sure hard work pays off for all Ohioans."

A spokesperson for the Brown campaign defended the senator's record and claimed his Republican opponent "only looks out for himself and his special interest allies."

"Ohioans know that Sherrod always fights for them and will stand up to anyone who gets in the way, which is why special interests are spending record amounts to defeat him," the spokesperson said. "While Bernie Moreno only looks out for himself and his special interest allies, Sherrod is fighting for stronger ethics and transparency rules for lobbyists, supports bipartisan legislation to crack down on foreign actors, and is fighting to lower costs for Ohioans by holding corporations accountable." 

Bernie Moreno and Sherrod Brown

L - Bernie Moreno R - Sen Sherrod Brown (Getty Images)

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The campaign pointed to Brown's support of the Lobbying Disclosure Improvement Act last year, which was bipartisan legislation aimed at cracking down on foreign actors lobbying and increasing disclosure requirements for foreign lobbyists. The Ohio senator also co-sponsored the Honest Leadership and Government Act, which overhauled congressional lobbying and ethics rules for Senators and their staff.

Reagan McCarthy, a spokesperson for Brown's GOP opponent Bernie Moreno, told Fox News Digital in a statement that, "Sherrod Brown parades around as an average Ohioan, but he is nothing more than a career politician who rewards the Washington swamp."

"In November, Ohioans will finally retire Sherrod after 50 years in politics and send an outsider to DC who will actually work for Ohio."

The race between Moreno and Brown is expected to be a close one as Republicans view it as one of their strongest opportunities to take back control of the Senate in November. The Cook Political report ranks the race as a "toss up."