Senate Minority Leader Mitch McConnell (R-Ky.) said in a speech Friday that President Obama probably didn't order the IRS's targeting of conservative groups, but that his White House created a "culture of intimidation" that resulted in the wrongdoing.

"No, I don’t believe that the president ever actually picked up a phone and told someone over at the IRS to slow-walk those applications or audit anybody," McConnell said at the American Enterprise Institute. "But the truth is, he didn’t have to. The message was clear enough."

McConnell later added: "There might be some folks out there waiting for a hand-signed memo from President Obama to Lois Lerner to turn up; don’t hold your breath."

Some Republicans have argued that the White House may have played a more direct role in the targeting, pointing in particular to then-IRS commissioner Douglas Shulman's frequent White House visits. And a recent CNN poll showed that 47 percent of Americans believe the White House ordered the extra scrutiny.

But while he acknowledged that Obama probably didn't personally order the targeting, McConnell said the the IRS' targeting of conservative groups is symptomatic of a larger problem in the administration.

He pointed to Obama directly naming people like the Koch brothers, suggesting Obama effectively placed a target on certain groups and that the IRS picked up on the signals.

"As serious as the IRS scandal is, what we’re dealing with here is larger than the actions of one agency or any group of employees," he said. "This administration has institutionalized the practice of pitting bureaucrats against the very people they’re supposed to be serving, and it needs to stop."

McConnell said the White House is "determined to shut up" its critics.

"Our ability to freely engage in civic life and to organize in defense of our beliefs is still under coordinated assault from groups on the left that don’t like the idea of anyone criticizing their aims, and from a White House that appears determined to shut up anybody who challenges it," McConnell said.

It's the second time McConnell has spoken out against the administration's alleged silencing of its critics. He gave a similar speech to AEI in June 2012.