Given the following context:

The film opens on 12 April 1945 with the death of Franklin Roosevelt and the succession of Harry Truman to the presidency. In Europe, the Germans are close to surrender, but in the Pacific the bloody battle for Okinawa is still underway and an invasion of the Japanese home islands is not foreseen until the autumn. American battle casualties have almost reached 900,000, with Japanese casualties at 1.1 million, and some 8 million Asian civilians have died in the war that began with Japan's invasion of Manchuria in 1931.
The new president knows nothing about the nuclear weapons being developed at Los Alamos, and he must soon decide on whether to use them and how. The US Secretary of War, Henry Stimson, has doubts even about the wisdom of the American fire-bombing raids on Japan.
"One of these Gadgets [bombs]", U.S. Secretary of State James F. Byrnes says, "could end the war in one blow." When nuclear physicist Leo Szilard delivers a petition signed by 73 scientists urging the president not to deploy the bomb, Byrnes tells him: "You do not spend two billion dollars and then show them [American voters] nothing." The film suggests that Byrnes never mentioned Szilard's visit to the president. Also urging deployment is Maj. Gen. Leslie Groves, director of the Manhattan Project. "We've come this far", Groves says; "there's no going back." A demonstration is ruled out because "it might be a dud."
In Japan, the strong man is Gen. Anami Korechika, the minister of war, who argues that if the homeland is defended at the cost of every Japanese, the Americans will tire of war and sue for peace. "Surrender is out of the question", he says. The voice of reason is the new civilian prime minister, Suzuki Kantaro, who says in private, "We must end this damned war."

answer the following question:

What is the full name of the person that the nuclear physicist urges not to use the bomb? 

Harry Truman