Sen. Bob Corker, the ranking member of the Foreign Relations Committee, is demanding to know why the U.S. government allegedly has made tens of millions of dollars in cash payments to Afghan President Hamid Karzai and his relatives, despite continued complaints of corruption at all levels of the Afghan government.

Exasperated that Obama administration officials have ignored three previous written requests for information about the payments over the last two months, Corker, R-Tenn., has placed a hold on $75 million in U.S. government funding for Afghanistan until the administration briefs him on the program.

“As a matter of oversight of U.S. foreign policy operations, I have repeatedly requested briefings and additional information on the nature and effect of this policy, classified and unclassified, as appropriate,” he said. “The administration’s lack of response to these requests, its apparent decision to flout the Foreign Relations Committee’s oversight and its inability (or unwillingness) to explain such a policy is unacceptable.”

The $75 million is intended for electoral programs in Afghanistan. Corker informed Secretary of State John Kerry, who previously was chairman of the Senate Foreign Relations Committee, as well as U.S. Agency for International Development Administrator Rajiv Shah, about the hold in a letter sent Monday.

“This hold will remain in place until such time as I receive sufficient information on these matters and sufficient assurances that there is a process in place to ensure our policy towards governance in Afghanistan is coherent and supports our national interests,” he wrote.

In early May, Karzai said he met with the CIA’s station chief in Kabul, who assured him that the agency would continue dropping off stacks of cash at his office, despite the uproar news of the payments stirred in Washington, the New York Times reported.

The CIA money, Karzai said at the time, was “an easy source of petty cash,” and at least some of it was used to pay off feuding warlords. Even though the U.S. likely used the alleged payments to maintain influence at the presidential palace, critics have said it undermined the overarching goal of U.S. operations in Afghanistan – to help set up a strong working government more popular among the people than the Taliban rule.