At the time in the 1920's, the Republican party had a straight run of three presidents; Warren Harding, Calvin Coolidge and Herbert Hoover. All three presidents shared the same ideology that the government should remain hands-off (or laissez-faire) towards the economy, being completely independent of it.
Since the economy was booming ever since World War I, there really was no need for any partial or heavy government influence in the economy. When the first signs of the Depression started to come around in the late 1920's, Herbert Hoover was the president. Growing up, he was a man who had done everything himself, and gotten out of man tough situations. With this mindset, he thought that the American people could do the same with the Depression, but was obviously very wrong. This was ultimately the last chance that the government had to avoid the Depression, and they missed it because of Hoover.
When the Depression was in full-swing, the only option for the American people was for the government to step in and help, and that was ultimately the reason for Franklin D. Roosevelt's success as president.