Republican presidential candidate Ben Carson slammed lawmakers for inviting a Muslim civil rights group to the State of the Union Tuesday night, calling the Council on American-Islamic Relations (CAIR) "not pro-American." Carson has urged federal officials to investigate CAIR, suggesting the Islamic advocacy group might have ties to terrorism.

“They have done things that are clearly, you know, not pro-American,” he said on CNN’s “New Day.” “These are people who I have called for an investigation of. We can’t now sit there and say these are buddy-buddies of ours, [so] let’s go ahead and investigate the thing. If they are our buddies, let’s put that clearly out there. And if they’re not our buddies, let’s not be giving them access to the ability to further carry on what they call a civilization jihad and to change us from a Judeo-Christian foundation to a Muslim foundation. We have got to be smarter than that.”

A CAIR spokesman said Carson was out of line. "You’ve got a presidential candidate whose campaign is circling the drain, and he’s doing anything he can do to spark some sense of relevance,” Ibrahim Hooper, the national communications director for CAIR, told Politico Tuesday. “Anti-Muslim bigotry worked for him in the past, so he thinks it may work for him again.”

Carson has in the past said a Muslim should not be president of the United States. After a backlash, he later clarified that any Muslim candidate should denounce Sharia law. Still, he has continued to take a tough stance on Muslim leaders. In December, Carson called for a federal probe into CAIR's work.

“The Department of State should designate the Muslim Brotherhood and other organizations that propagate or support Islamic terrorism as terrorist organizations and fully investigate the Council on American-Islamic Relations as an offshoot of the Muslim Brotherhood and a supporter of terrorism,” Carson wrote at the time.

Democratic Reps. Zoe Lofgren of California and Alcee Hastings of Florida invited the two CAIR officials to Obama’s final speech at the Capitol Tuesday. The CAIR officials represent CAIR chapters in each respective state, the Hill reported.

Other conservatives have slammed the Democratic lawmakers for inviting Muslim activists to the State of the Union. "This is an obscene gesture and an affront to all those who have suffered at the hands of terrorists. This invitation not only sends the message to our enemies that terrorism is rewarded, but it emboldens those whose stated goal is to destroy the West. That these Islamists are being allowed into Congress makes a mockery of the safety precautions associated with the event," wrote Joe Kaufman, a former Republican candidate for the U.S. House of Representatives in Florida’s 23rd Congressional District, for FrontPage mag. 

Anti-Muslim sentiment in the U.S. has been on the rise in recent years, according to poll data. Favorable attitudes toward American Muslims fell from 48 percent to 33 percent since 2010, according to a December poll conducted by Zogby Analytics, a nonpartisan research firm based in New York. The poll, which surveyed some 1,000 adults online Dec. 7, found 51 percent of Democrats had favorable sentiments toward Arab-Americans, compared with 34 percent for Republicans.