"This danger to Kennedy is believed to increase or decrease in relation to the level of his public activity and visibility. For example, when Kennedy made a strong statement about Vietnam a short while ago his “'hate mail” rose in volume, whereas when he was defeated as whip last January it slackened. If Kennedy were to become a declared candidate for President, it seems reasonable to assume, he would be in still greater danger not only because he would then be much more active on the public stage but also because he would be adding another element to the symmetry proposition — becoming the third brother to associate himself with the office of the President. Even now, Kennedy receives more hate mail and threats against his life than anyone else in the country except the President. According to one count made last February, between the time of the assassination of President Kennedy and 1971 Kennedy received 355 threats serious enough to be investigated by the Secret Service. (The next two most threatened Senators were Eugene McCarthy and Barry Goldwater, who received 99 and 94 threats, respectively, during the same period.) The Secret Service does not have the authority to protect members of Congress, but traditionally it has investigated threats to all public officials on the ground that persons making such threats are a potential danger to the President and the Vice President."