The International Business Times:

...The majority of the attacks have focused on Paul's non-interventionist foreign policy views and on the racist and anti-Semitic statements made in his old newsletters, which he has disavowed and maintained he was unaware of. His economic and social policies have been addressed less frequently.

One group, however -- the National Organization for Marriage -- is homing in on Paul's stance on same-sex marriage. As a libertarian, he believes the issue should be left up to the states, and he and Huntsman are the only candidates who have not signed the group's pledge to support a federal constitutional amendment banning same-sex marriage.

NOM just released a TV ad blasting Paul's views on marriage, and in an accompanying press release, NOM President Brian Brown called those views "far out of the mainstream" and "simply unacceptable."

"Marriage between one man and one woman has been the foundation of American society and American families," Brown said. "It is truly radical for a serious presidential candidate to blithely cast marriage aside, suggesting that any private arrangement between adults can be called marriage."