So glad you asked!
Robert M. La Follette (1855-1925) was a Republican politician from Wisconsin who was one of the leading figures of the Progressive movement. La Follette is largely responsible for the use of an open primary system over a caucus system to nominate candidates for most offices around the country.
Through his early political experiences, La Follette started to recognize the negative influence money and political machines had on representative democracy. While running for governor in the 1890s, La Follette came to believe that his opponents at the Republican nominating convention had bribed delegates that were pledged to support La Follette, causing him to lose the nomination. More broadly, he recognized that the caucus system favored organized, wealthy interests over the voters at large.
In searching for a solution to reclaim democracy for the voters, La Follette found the primary system. He made it a central part of his platform and worked diligently to pass it into law. He faced significant opposition, battling members of the state legislature over multiple election cycles before enacting it into law.
While the primary system today certainly has it flaws, La Follette’s fight is a great example of someone identifying a problem, realizing that the system as a whole needed an upgrade and using his political will to get it done.
The quote on this page comes from his 1897 speech “The Danger Threatening Representative Government,” where he introduced the idea of a primary.
The picture is from Wikipedia.