Sen. Al FrankenAlan (Al) Stuart FrankenDemocrats turn on Al Franken Schumer called, met with Franken and told him to resign Overnight Finance: Trump says shutdown 'could happen' | Ryan, conservatives inch closer to spending deal | Senate approves motion to go to tax conference | Ryan promises 'entitlement reform' in 2018 MORE (D-Minn.) asked the Federal Election Commission (FEC) on Wednesday to investigate the U.S. Chamber of Commerce's funding for its political activities.

Franken wrote FEC Chairman Matthew Petersen to ask for a probe into whether the Chamber is indirectly using money from foreign corporations to finance its political operations, which have largely targeted Democrats, this cycle.

"I am writing to ask that you investigate these claims, enforce existing laws and regulations prohibiting foreign spending in American elections, and strengthen those very last through new regulations and policy guidance," Franken wrote.

The senator's letter comes on the heels of a report by the liberal blog ThinkProgress that suggested the Chamber, through foreign-based affiliates, has raised money for its general operations, a pool of money that is "commingled" with the business advocacy group's political spending fund.

Franken noted that while that practice is not necessarily illegal (as long as a group employs  a "reasonable accounting method" for its funds), the FEC should investigate to ensure no foreign funds flowed to the Chamber's political operations.

"If such an accounting is impossible, and these foreign funds were in fact used in American elections, these actions would violate federal law as interpreted by decades-old commission guidance," he wrote. "I respectfully request that you promptly investigate these claims and further request that you report your findings to my office."

Tita Freeman, the chamber's vice president of communications and strategy, said the accusations are "completely erroneous."

"AmChams are independent organizations that do not fund political programs in the United States," Freeman said in a statement. "We’re careful to ensure that we comply with all applicable laws. No foreign money is used to fund political activities. All allegations to the contrary are totally and completely false."

The Chamber has suffered from an occasionally tense relationship with President Obama and congressional Democrats. Sen. Charles SchumerCharles (Chuck) Ellis SchumerAmerica isn't ready to let Sessions off his leash Schumer celebrates New York Giants firing head coach: ‘About time’ GOP should reject the left's pessimism and the deficit trigger MORE (D-N.Y.) had accused the business group of acting as an arm of the GOP during the 2008 elections, and the Chamber has poured money into efforts to fight healthcare and Wall Street reform bills that made their way through Congress during the past 20 months.