Final answer:
The reformers had a significant impact when fighting for the 17th Amendment by establishing the direct election of U.S. senators by the people.
Step-by-step explanation:
The reformers had a significant impact when fighting for the 17th Amendment. The 17th Amendment established the direct election of U.S. senators by the people, replacing the previous system of state legislatures choosing senators. This reform aimed to make the process more democratic and give citizens more power in selecting their representatives.