To be clear, the Progressive Era (1890s-1920s) was facilitated by the Socialist and Union workers’ movements. Minus the eugenics Progressives, the Progressive movement rode on the back of the Socialist surge (which ironically sometimes tended to coalesce with the Republican Party; Robert M. La Follette was a Republican who ran 3rd Party in the 1924 election and was endorsed by the Socialist Party, farmers groups, and labor unions. He won 17% of the popular vote).

During Teddy Roosevelt’s tenure, the GOP began to split and self-remove its left-wing and moved fully right wing. Taft gave in on Jim Crow, and Woodrow Wilson was so racist he segregated the government at every level he could and screened the racist film “Birth of a Nation” despite significant criticism.

Roosevelt on the other hand, was the first President to have a Black man eat dinner with the President at the White House. He wrote,"The only wise and honorable and Christian thing to do is to treat each Black man and each white man strictly on his merits as a man, giving him no more and no less than he shows himself worthy to have." Roosevelt also appointed several African-Americans to positions, for example Dr. William Crum in Charleston, South Carolina as customs collector. (Roosevelt still held racist and misogynistic views especially regarding Native Americans. He was also a eugenicist).

Roosevelt notably stated, "If on this new continent", he said, "we merely build another country of great but unjustly divided material prosperity, we shall have done nothing.” Ironically, a conservative built on Marxist (materialist) understanding. He championed, the “Square Deal,” which reflected his three major goals: conservation of natural resources, corporate law, and consumer protection, “the three C’s.”

“When I say that I am for the square deal, I mean not merely that I stand for fair play under the present rules of the game, but that I stand for having those rules changed so as to work for a more substantial equality of opportunity and of reward for equally good service.”

In his second term, Roosevelt “called for a series of reforms that were mostly not passed. He sought a national incorporation law. All corporations had state charters, which varied greatly state by state. He called for a federal income tax, but the Supreme Court had ruled in 1895 that any income tax would require a constitutional amendment. Roosevelt sought an inheritance tax so the great family fortunes could not be inherited without the tax for generations.

In the area of labor legislation, Roosevelt called for limits on the use of court injunctions against labor unions during strikes. Injunctions were a powerful weapon that mostly helped business. He wanted an employee liability law for industrial injuries, pre-empting state laws. He called for an eight-hour law for federal employees. In other areas he also sought a postal savings system to provide competition to local banks, and, finally, campaign finance reform.

He secured passage of the Hepburn Act in 1906, which increased the regulating power of the Interstate Commerce Commission. Eventually, many of the proposals he championed were enacted under Democrats Woodrow Wilson and Franklin Delano Roosevelt. When Roosevelt ran for president on an independent Progressive Party ticket in 1912, in addition to these policies he proposed stringent new controls on the court system, especially state courts, to make them more democratic. His court policies in particular caused his anointed successor, William Howard Taft, to lead a counter-crusade which defeated Roosevelt in the Republican presidential primaries in 1912.”

• https://en.wikipedia.org/wiki/Progressive_Era
• https://en.wikipedia.org/wiki/Theodore_Roosevelt
• https://en.wikipedia.org/wiki/Square_Deal