There are at least two ways to interpret this question. First, we can interpret it to ask why voters changed from electing conservatives to electing a liberal in 1932. Second, we can interpret it to ask what actual changes show that the government went from being conservative to being liberal. I will answer both of these questions.
The voters changed from electing conservatives to electing a liberal because of the Great Depression. Beginning in late 1929, the economy had crashed terribly and had not returned to normal. Because conservative presidents had presided over the time before the crash, and because the conservative President Hoover had not managed to fix the Depression in the three years that he had in office after the crash, voters decided to go with a liberal.
There were many actual changes that showed that the government was becoming much more liberal in its economy policy. While people often do not realize that President Hoover did involve the government in trying to fix the economy, it is certainly true that President Roosevelt got the government much more involved in the economy. All you have to do is to look at the array of New Deal programs that Congress passed in his administration. Among other things, the government:
- Paid farmers to grow fewer crops and to kill livestock. (AAA)
- Paid young men to go out and do things like taking care of forests and creating picnic areas and other recreational opportunities for people. (CCC)
- Built dams to control floods and to bring electricity to rural areas (TVA and others).
- Insured bank deposits so that people would not lose their money in bank runs. (FDIC)
- Created pensions for retired people. (Social Security)
- Gave money to the states to hire unemployed people to do relatively low skilled jobs. (FERA)
The New Deal did all this and more, showing that the government had moved towards a much greater level of involvement in the economy. This shows that the government became more liberal after 1932.