Sen. JD Vance, R-Ohio, is expected to send a letter Thursday morning to the IRS commissioner demanding a halt to “harassment” of conservative organizations. 

Sen. Mike Braun, R-IN, cosigned the letter. 

The letter comes after the IRS informed the American Accountability Foundation (AAF) in a letter, which AAF shared with Fox News Digital, that it would launch an investigation into the watchdog group Sept. 14.

The IRS notified AAF it would inquire whether the organization “operates in accordance with section 501(c)(3) of the Internal Revenue Code,” according to the letter.

“But, to date, the IRS has neither presented any evidence that AAF has failed to observe the requirements of section 501(c)(3) nor explained why AAF may be at risk of failing to observe those requirements,” Vance wrote in the letter.

“I do not need to remind you that the AAF audit follows on the heels of an ugly chapter in the IRS’s history, during which the agency unfairly targeted conservative groups for scrutiny on the basis of their views,” he wrote.

Vance seeks information from the IRS about potential bias in selecting audits, citing historical instances of IRS bias against conservative organizations. One example Vance cites was in 2017 when the agency subjected conservative groups applying for tax-exempt status to heightened scrutiny and significant delays. 

The IRS admitted to targeting these groups based on their conservative viewpoints beginning in the 2010s, leading to a cleanup of the agency’s top leadership, the letter noted.

Additionally, he inquired whether the IRS has declined to pursue audits of progressive or left-wing nonprofits and seeks explanations for those decisions.

The AAF has published exposes on several Biden nominees for senior positions, which led him to withdraw some of their candidacies. It has also published emails revealing Sen. Sheldon Whitehouse, D-R.I., urged the IRS to audit conservative organizations, as reported last November. 

In June, the AAF launched an investigation into the IRS for building a government-run tax filing program that critics argue would give the agency too much power.

AAF made public records requests, first obtained by Fox News Digital, seeking communications and other documents from the IRS and the Office of Management and Budget concerning the creation of an IRS-run electronic tax filing system, commonly referred to as “direct file.”

The Inflation Reduction Act, a mammoth Democrat-backed spending bill signed into law last year, included $15 million for the IRS to look into creating a free direct tax return system. Specifically, the legislation required a study by an independent third party examining the idea’s feasibility, as well as a report by the IRS for Congress assessing the study, the cost of such a system and taxpayer opinions based on surveys.

An IRS spokesperson told Fox News Digital the IRS cannot confirm or deny current audits.