By Erik Derr (staff@latinospost.com) | First Posted: May 11, 2013 05:18 PM EDT

The Internal Revenue Service is apologizing for singling out so-called "Tea Party" conservative political groups for additional reviews during the 2012 election under the auspices of seeing if they were violating their tax-exempt status.

Lois Lerner, who heads the IRS unit that oversees tax-exempt groups, admitted organizations that included the words "tea party" or "patriot" in their applications for tax-exempt status were inappropriately targeted for additional reviews, NBC News is reporting.

Speaking at a conference in Washington, Lerner said the stepped-up review guidelines were initiated by low-level workers in Cincinnati. She said the practice was wrong and she apologized.

Many conservative groups had complained during the election that they were being harassed by the IRS, which asked them an inordinate number of questions to justify their tax-exempt applications.

Certain tax-exempt charitable groups can hold political activities, but politicking cannot be their primary activity.

Senate Minority Leader Mitch McConnell released a statement calling on the Obama administration to conduct a review of "these thuggish practices" by the IRS:

"Today's acknowledgement by the Obama administration that the IRS did in fact target conservative groups in the heat of last year's national election is not enough. Today, I call on the White House to conduct a transparent, government-wide review aimed at assuring the American people that these thuggish practices are not underway at the IRS or elsewhere in the administration against anyone, regardless of their political views.

"Last year, amid reports that the Obama administration was using the levers of executive power to harass conservative political groups in Kentucky and elsewhere, I issued a very public warning to the administration that the targeting of private citizens on the basis of their political views would not be tolerated. Today's apology by the IRS is proof that those concerns were well founded. But make no mistake, an apology won't put this issue to rest. 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[sic] sufficient response to what we now know took place at the IRS. This kind of political thuggery has absolutely no place in our politics."