"The Committee will continue to examine the threat of Islamic radicalization," King writes, "And I will not allow political correctness to obscure a real and dangerous threat to the safety and security of the citizens of the United States."

Today, The Times reported that King planned to call mostly Arabs and Muslims to testify, telling the paper that he thought it would send a powerful signal to domestic Islamic extremists to see their co-religionists testifying.

Added King in his letter: "The homeland has become a major front in the war with Islamic terrorism and it is our responsibility to fully examine this significant change in al Qaeda tactics and strategy. To include other groups such as neo-Nazis and extreme environmentalists in this hearing would be extraneous and diffuse its efficacy. It would also send the false message that our Committee believes there is any threat equivalency between these disparate groups and Islamist terrorism."