Khrushchev continued to insist on no more than three. Kennedy was willing to reduce the number to six, though this was not clearly communicated to the Soviet Union. On 20 April 1963, Khrushchev withdrew support for three inspections entirely. Progress was further complicated in early 1963, as a group in the US Congress called for the Soviet proposal to be discarded in favor of the Geneva System. On 27 May 1963, 34 US Senators, led by Humphrey and Thomas J. Dodd, introduced a resolution calling for Kennedy to propose another partial ban to the Soviet Union involving national monitoring and no on-site inspections. Absent Soviet agreement, the resolution called for Kennedy to continue to "pursue it with vigor, seeking the widest possible international support" while suspending all atmospheric and underwater tests. The effect of the resolution was to bolster the general push for a test ban, though Kennedy initially was concerned that it would damage attempts to secure a comprehensive ban, and had administration figures (including the Joint Chiefs of Staff) reiterate a call for a comprehensive ban. That same spring of 1963, however, Kennedy had sent antinuclear activist Norman Cousins to Moscow to meet with Khrushchev, where he explained that the political situation in the US made it very difficult for Kennedy agree to a comprehensive ban with Khrushchev's required terms. Cousins also assured Khrushchev that though Kennedy had rejected Khrushchev's offer of three yearly inspections, he still was set on achieving a test ban. In March 1963, Kennedy had also held a press conference in which he re-committed to negotiations with the Soviet Union as a means of preventing rapid nuclear proliferation, which he characterized as "the greatest possible danger and hazard." One of Kennedy's advisors, Walt Whitman Rostow, advised the President to make a test ban conditional on the Soviet Union withdrawing troops from Cuba and abiding by a 1962 agreement on Laos, but Kennedy opted instead for test-ban negotiations without preconditions. On 10 June 1963, in an effort to reinvigorate and recontextualize a test ban, President Kennedy dedicated his commencement address at American University to "the most important topic on earth: world peace" and proceeded to make his case for the treaty. Kennedy first called on Americans to dispel the idea that peace is unattainable. "Let us focus instead on a more practical, more attainable peace," Kennedy said, "based not on a sudden revolution in human