Probably the most important political issue of this period was the issue of the gold standard versus free silver. This pitted business interests against farmers. The farmers wanted silver money to be coined so that the value of the dollar would decline and it would be easier for them to pay off their loans. Business interests wanted a strong and stable currency. This issue played out over a number of presidential elections.
A second important issue was the issue of regulation of railroads and other major utilities. This was another major issue for populists. The populists (mainly farmers) wanted the government to regulate railroads because the farmers needed the railroads to get their crops to market. Because of this, the railroads could charge very high prices to farmers. The farmers felt that they were being unfairly exploited and wanted the government to prevent this.
These were the two most important political issues of the time you are asking about.