Congress on Friday launched a wide-ranging probe into a secret Obama administration-funded campaign to unseat Israeli Prime Minister Benjamin Netanyahu, according to information exclusively obtained by the Washington Free Beacon.

The probe comes on the heels of an internal government report determining that the State Department provided hundreds of thousands to an organization that plotted to unseat Netanyahu in the country’s 2015 election.

Obama administration officials were found to have deleted emails from State Department accounts containing information about its relationship with OneVoice, the non-profit group that led the effort.

OneVoice, which was awarded $465,000 in U.S. grants through 2014, has been under congressional investigation since 2015, when it was first accused of funneling some of that money to partisan political groups looking to unseat Netanyahu. This type of behavior by non-profit groups is prohibited under U.S. tax law.

A group of nine leading lawmakers led by Sen. David Perdue (R., Ga.) are now formally petitioning the State Department to come clean about the effort and provide answers about how U.S. taxpayer dollars were permitted to be spent on an organization working against the elected leader of America’s closest Middle East ally, according to a readout of the investigation obtained by the Free Beacon.

"State Department officials failed to properly vet the OneVoice grant proposal because they failed to properly conduct an analysis of risks in the pre-award phase," the senators wrote in a letter to Secretary of State John Kerry. "Unfortunately, it seems that inconsistency and apathy toward oversight of such grants at the State Department is not new. Our aid dollars should be going toward solving real problems, not contributing to the destabilization of allied governments."

The lawmakers—including Sens. Ted Cruz (R., Texas), Mark Kirk (R., Ill.), Orrin Hatch (R., Utah), Mike Lee (R., Utah), and Johnny Isakson (R., Ga.) among others—wrote that the State Department turned a blind eye to OneVoice’s highly partisan activities and failed to perform proper oversight about how U.S. funds were being spent by the group.

"State Department officials utterly failed to follow established procedures and guidelines to properly identify, mitigate, or guard against any risk that OneVoice would misuse these funds before, during, and after the grant period," the letter said. "As a direct result of these failures, OneVoice was able to use the more than $300,000 grant to build campaign infrastructure and resources which later were deployed in support of a negative campaign against Prime Minister Benjamin Netanyahu, his Likud Party, and the democratically elected coalition government of Israel during the 2015 Israeli parliamentary election."

State Department officials were aware of OneVoice’s partisan activities, but still permitted the grant money to be awarded, according to the senators, who are pushing for the administration to take disciplinary action against the officials involved.

"Despite knowledge of such activities, State Department officials failed to adequately document any assessment of the risk that OneVoice might continue obstructive efforts against a certain political party in the event of an election," the letter stated.

"State Department grant policies and procedures are in place to ensure that taxpayer dollars are used to fund U.S. government initiatives and further U.S. interests," the letter said.

The senators require the State Department to answer a series of questions about the grant, including how it vetted OneVoice and why proper oversight methods were not employed.

They also are seeking to determine what "disciplinary action" is being taken against U.S. officials who knew about the plan to unseat Netanyahu but failed to take action to report this behavior.