Roll Call:

As evidence mounts that the IRS is more closely scrutinizing politically active nonprofit groups, Republicans on Capitol Hill have lashed out with assaults on the tax agency and fresh demands for an explanation.

The IRS may have stepped over the line this year by asking conservative groups applying for tax-exempt status to hand over the names of their donors, wrote Sen. Orrin Hatch(Utah) and 10 other Republican Senators in a letter this week to IRS Commissioner Douglas Shulman.

“Unfortunately, the public release of private donor information exposes citizens to possible harassment and intimidation by those who oppose the goals of the charitable organization,” wrote Hatch, ranking member of the Finance Committee. It’s the second letter from Hatch to Shulman on the topic this year.

The letter is the latest in a string of attacks by conservatives on and off Capitol Hill, including Senate Minority Leader Mitch McConnell (Ky.), on initiatives that would shed more light on political spending. In a strongly worded speech last week at the American Enterprise Institute, McConnell accused President Barack Obama of creating an “enemies list” and “attempting to change the First Amendment.”

... McConnell cast the IRS as the “speech police” for sending lengthy questionnaires to “dozens of tea-party-affiliated groups” seeking tax exemptions. He also accused the agency of leaking confidential tax information, citing reports last month that a leadership PAC run by presumptive GOP presidential nominee Mitt Romney had donated $10,000 to the National Organization for Marriage, which opposes same-sex marriage.