"The privacy interests of donors is widely recognized and valued. Various public policy initiatives have rightly encouraged donations to social welfare organizations, and these efforts are threatened when private information about donors is not adequately protected," the letter states.

The new letter, from Sen. Orrin HatchOrrin Grant HatchPress: Forget bipartisanship — it's dead! Privatization of foster care has been a disaster for children Remembering Ted Kennedy highlights decline of the Senate MORE (R-Utah) and other GOP senators, says that, by requesting the confidential donor names, the agency has set in motion a process that will result in the names being available for public viewing at the IRS when the investigated groups are approved to become a 501(c)(4).

"The IRS appears to be circumventing the statutory privacy protections that Congress has long provided donors," exposing the donors to "possible harassment," the Republicans said."The public release of private donor information exposes citizens to possible harassment and intimidation by those who oppose the goals of the charitable organization."

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Republicans and Democrats on Capitol Hill have been clashing over 501(c)(4) and other tax-exempt groups, some of which are spending millions of dollars this year on election advertising. 

The IRS currently says that the primary purpose of 501(c)(4) groups should not be political, which has led some legal analysts to assert that those organizations should use less than 50 percent of their budget on political causes.  

Watchdogs argue groups are misusing the 501(c)(4) tax-exempt status to keep their donors secret as they spend millions on election ads. 

The Republican senators requested that the IRS provide the statutory authority to require donor names, the frequency of requests for the information, and which officials were involved in requesting and approving the "questions requesting donor names," among other issues.

Along with Hatch, the Republican senators who signed the letter were Mitch McConnellAddison (Mitch) Mitchell McConnellWhen it comes to Georgia's voting law, keep politics out of business Pelosi to offer even split on 9/11-style commission to probe Capitol riot Senate GOP crafts outlines for infrastructure counter proposal MORE (Ky.), Mike EnziMichael (Mike) Bradley EnziThe Hill's Morning Report - Presented by the National Shooting Sports Foundation - CDC news on gatherings a step toward normality Lummis adopts 'laser eyes' meme touting Bitcoin Senate swears-in six new lawmakers as 117th Congress convenes MORE (Wyo.), Lamar AlexanderLamar AlexanderSenate GOP faces retirement brain drain The Hill's Morning Report - Presented by the National Shooting Sports Foundation - CDC news on gatherings a step toward normality Blunt's retirement deals blow to McConnell inner circle MORE (Tenn.), John CornynJohn CornynCornyn, Sinema to introduce bill aimed at addressing border surge Bipartisan group of senators holds immigration talks amid border surge House votes to extend ban on fentanyl-like substances MORE (Texas), Kay Bailey Hutchison (Texas), Jon Kyl (Ariz.), Bob CorkerRobert (Bob) Phillips CorkerFox News inks contributor deal with former Democratic House member Senate GOP faces retirement brain drain Roy Blunt won't run for Senate seat in 2022 MORE (Tenn.), Pat RobertsCharles (Pat) Patrick RobertsSenate GOP faces retirement brain drain Roy Blunt won't run for Senate seat in 2022 Lobbying world MORE (Kan.), John ThuneJohn Randolph ThuneSenate GOP keeps symbolic earmark ban Senate GOP crafts outlines for infrastructure counter proposal On The Money: Senate GOP faces post-Trump spending brawl | Senate confirms SEC chief Gensler to full five-year term | Left-leaning group raises concerns about SALT cap repeal MORE (S.D.) and Rand PaulRandal (Rand) Howard PaulHillicon Valley: Tech companies duke it out at Senate hearing | Seven House Republicans vow to reject donations from Big Tech Senate panel greenlights sweeping China policy bill Senate GOP keeps symbolic earmark ban MORE (Ky.).

— Bernie Becker contributed to this report.