His political activism prompted the US State Department to deny him a passport in 1952, when he was invited to speak at a scientific conference in London. In a speech before the US Senate on June 6 of the same year, Senator Wayne Morse publicly denounced the action of the State Department, and urged the Passport Division to reverse its decision. Pauling and his wife Ava were then issued a "limited passport" to attend the aforementioned conference in England. His full passport was restored in 1954, shortly before the ceremony in Stockholm where he received his first Nobel Prize.