(CNN) – All forty-five Republican senators are demanding President Barack Obama's administration comply with requests for information as Congress probes the Internal Revenue Service's targeting of conservative groups applying for tax exempt status.
In a letter addressed to Obama, the Republicans decry the IRS's actions and say the White House and the Treasury Department must make all employees available for interviews by investigators.
"This type of purely political scrutiny being conducted by an Executive Branch Agency is yet another completely inexcusable attempt to chill the speech of political opponents and those who would question their government, consistent with a broader pattern of intimidation by arms of your administration to silence political dissent," the senators wrote.
Multiple Congressional inquiries into the IRS's practices are already on the books: The Democrat-led Senate Finance Committee will hold a hearing into the matter next Tuesday, and the GOP-chaired House Oversight Committee will convene a hearing next Wednesday.
On Tuesday, Attorney General Eric Holder also said the Federal Bureau of Investigation would launch its own criminal probe into whether IRS employees politically targeted the conservative groups.
In their letter, the Republican senators wrote that "the American people deserve to know what actions will be taken to ensure those who made these policy decisions at the IRS are being held fully accountable and more importantly what is being done to ensure that this kind of raw partisanship is fully eliminated from these critically important non-partisan government functions."
All requests from Congressional investigators must be fulfilled, the lawmakers wrote, and IRS employees involved in targeting the groups must be able to submit to interviews or testimony.
"It is imperative that the Administration be fully forthcoming to ensure that we begin to restore the confidence of our fellow citizens after this blatant violation of their trust. We look forward to working on this critical issue with the Administration's full cooperation," the letter read.