more than 2.3 million muslims in the united states, that's about .6% of the population. roughly two thirds of muslims in america are immigrants. i want to bring in an expert on extremism, mark potoch with the southern poverty law center, rather. one of the most highly regarded nongovernmental operations monitoring hate groups. he joins us from montgomery, alabama. if you can from your study of tracking radical groups, potentially hate groups, what do you think of this hearing? is al qaeda radicalizing muslims? is that the biggest home grown terrorism threat right now? >> well, i think it's not our biggest domestic terror threat. i think that pretty clearly comes from the radical right in this country. although i would certainly not minimize the threat of jihadist terrorism in this country. we have seen a fair amount of it