What were Joseph McCarthy's motives?

Joseph McCarthy was a senator from Wisconsin who led the Red Scare. This permeated all levels of society. McCarthy greatly exaggerated communism. He was an alcoholic. In 1950 he was facing a losing campaign. He claimed to know communists in the American government and also claimed that China fell to communism because of these people; He was lying though. Truman called him fraud but people still bought into his ideas. McCarthyism was successful because it offered easy answers and explanations for why China fell to communism and why we couldn't bring capitalism to Korea. There was partial truth to the need of fear, because there were spies caught spying on our atomic weapons. McCarthyism started to decline after Republicans cut off his support and he attacked the military and the Marshal Plan. As a result of McCarthyism, the state department loses the Asian experts and Americans learn a lesson that not everything is a communist plot.