What issue played a major role in the democratic party split

Answer: Civil Rights

Explanation: By the 1960s, the Democratic Party was made up of two distinct groups. One was the traditional base of the party, that is, white Southern conservatives. The other was progressives that made their mark under Roosevelt.

By the 1960s, the issue of Civil Rights had split the two groups as white Southern Conservatives were largely opposed to the issue of Civil Rights. Republicans, sensing this split, started to play towards the Southerners in what is now known as the "Southern Strategy."

The end result is that a split occurred and Southern Democrats left the party to become Republicans.