Kenneth H. answered 09/27/19
20 + Years Social Studies Teaching Experience including AP
There are several things to point out in addition to Chris E's fine answer, above.
National elections were very close contests in this period, so the Democrats and Republicans were very general in their issues. That caused 3rd parties to develop, which focused on particular issues which the 2 major parties were afraid of dealing with. Hence the development of the Greenback Labor Party, and Farmers'Alliance. The ideas of these parties were eventually absorbed by one or more or both of the 2 major parties.
In terms of economic and business policy, the government went from laissez-faire (hands-off) to government regulation (Interstate Commerce Act). How did Presidents react to labor disputes--sided with business and sent troops to break up strikes.
Look into the influence of Civil War veterans on elections and Republicans (Waving the Bloody Flag).
Creation of the Liberal branch of the Republican Party, influence of the "loco-focos", and the creation of the Greenback Labor Party.
Checks and balances: A very conservative Supreme Court strikes down Reconstruction laws, and favors laissez-faire business policies. The Congress reacts by passing laws about business regulation.
Consider also how the Pendleton Act affects the Executive Branch by finding a way to slowly get rid of the spoils system for government jobs.
Athiphat K.
Thank you so much, both of you saved my life.09/27/19