Why did progressive movement want the direct election of senator?

The Progressive era was an Era that lasted from 1820 to 1920, it was a collection of ideas and activities about how to fix many problems in American society.

They aimed to stop Senate corruption because, at that time, political machines often influenced the election of senators in exchange for federal contracts and jobs. So the progressists proposed the direct election of senator by all states voters. This was passed by the 7th Amendment.