Gagarin's flight changed this; now Kennedy sensed the humiliation and fear on the part of the American public over the Soviet lead. He sent a memo dated April 20, 1961, to Vice President Lyndon B. Johnson, asking him to look into the state of America's space program, and into programs that could offer NASA the opportunity to catch up. The two major options at the time seemed to be, either establishment of an Earth orbital space station, or a manned landing on the Moon. Johnson in turn consulted with von Braun, who answered Kennedy's questions based on his estimates of US and Soviet rocket lifting capability. Based on this, Johnson responded to Kennedy, concluding that much more was needed to reach a position of leadership, and recommending that the manned Moon landing was far enough in the future that the US had a fighting chance to achieve it first.
President Kennedy sent a letter on April 20, 1961 to who about the US's space program?
Vice President Lyndon B. Johnson