In Chapter 13, how and why was Harry S. Truman chosen to be Roosevelt's vice president?

Roosevelt knew that he would not live to finish his fourth term. So he wanted a vice president who was less liberal than the current vice president and less inclined to align himself with the labor movement. So Roosevelt choose Truman. When Truman was asked to take the job, he refused at first because he knew how precarious Roosevelt's health was. However, he was persuaded to take the job.