Update: White House spokesman Jay Carney says an inspector general is looking into the matter.

Senate Minority Leader Mitch McConnell, R-Ky., is calling on the Obama administration to conduct a government-wide probe in the wake of an admission by the Internal Revenue Service that it targeted conservative groups.

The IRS apologized on Friday for inappropriately flagging conservative political groups for additional reviews during the 2012 election to see if they were violating their tax-exempt status.

Lois Lerner, who heads the IRS unit that oversees tax-exempt groups, said organizations that included the words “tea party” or “patriot” in their applications for tax-exempt status were singled out for additional reviews.

Lerner said the practice, initiated by low-level workers in Cincinnati, was wrong and she apologized while speaking at a conference in Washington.

McConnell says the admission is proof that his earlier concerns were well founded, adding the White House needs to review the agency’s actions.

“Now more than ever we need to send a clear message to the Obama administration that the First Amendment is non-negotiable, and that apologies after an election year are not an sufficient response to what we now know took place at the IRS,” he says. “This kind of political thuggery has absolutely no place in our politics.”

Several conservative groups and Republican leaders complained of harassment by the IRS last year, arguing the federal agency was asking an inordinate amount of questions to justify their tax-exempt status.

During a fiery speech last summer, McConnell said the Obama administration was unfairly targeting tea party groups through the IRS. He later accused the White House of violating their First Amendment rights and compared the agency’s actions to the Nixon administration.

At the time, the IRS denied it was examining those organizations based on their political views.

Certain tax-exempt charitable groups can conduct political activities but it cannot be their primary activity.