Which was the main issue that divided presidential candidates of the democratic and republican parties in the late nineteenth century?
going to war
supreme court rulings
lowering or raising tariffs
newspaper coverage of scandals

The main issue that divided presidential candidates of the Democratic and Republican Parties in the late nineteenth century was about lowering or raising tariffs.

The Democratic candidates defended a progressive tax, and did not oppose the tax increase to finance the government.

On the other hand, Republicans favored a "fixed tax" (same tax rate regardless of income), and opposed the increase in taxes.

i believe the answer is:

-   william jennings bryan is a democrat while mckinley was a republican

at that time, the segment of population that choose for democratic party were the voters with low economic background and vice versa

- william jennings has support of populists and wants to have inflation to farmers while mckinley has support of bankers and businessmen , doesn't want inflation

the fixed value of gold make the large business able to stack up their gold without   being worried that it would devaluated.

- william jennings supported the silver standard while mckinley supported the gold standard

according to jenning, using other metal beside gold could the poor people to have more purchasing power and them advance in the society.