Huma Abedin, a deputy chief of staff to Secretary of State Hillary Clinton, is under police protection, the New York Post reports.
A man described only as a Muslim from New Jersey was questioned by New York City Police and the State Department over allegations that he had made threats to Abedin. He has not been charged, the paper said.
It is not known if the alleged threats against Abedin are connected to events that put her in headlines last week.
Senator John McCain (R-Arizona) took to the floor of the Senate on Wednesday to defend Abedin against doubts cast on her State Department security clearance by Minnesota congresswoman and McCain's fellow failed Republican presidential hopeful Michele Bachmann.
Abedin was named in June 13 letters co-signed by Bachmann and four other House Republicans and sent to several government agencies. The letters questioned how she was able to get security clearance in light of family ties to the Muslim Brotherhood.
McCain decried Bachmann's singling out of Abedin as "an unwarranted and unfounded attack on an honorable woman, a dedicated American, and a loyal public servant."
Bachmann has issued a statement saying that her remarks are being distorted, and has posted copies of each letter to her website.
Abedin, 37, was born in Michigan and raised in Saudi Arabia by Muslim parents. She returned to the US to attend George Washington University, and has worked for Hillary Clinton in one capacity or another since interning at the White House in 1996.
She is no stranger to unwanted publicity. She is married to Representative Anthony Weiner of New York, who was forced to resign last year when it emerged that he had engaged in lewd Twitter activity with various women. It was revealed during the media frenzy that Abedin was expecting the couple's first child. She has remained by Weiner's side, and delivered a baby boy in December 2011.