It so happens that the Left invented this phrase: it entered Communist lingo in the 1930s to praise loyalty to the party line.
But eventually politically correct turned against them.
By the 90s, it was used mainly by the Right as a kind of battle cry of the Culture Wars.
Here's President George H. W. Bush, in a 1991 commencement speech at the University of Michigan:
"The notion of political correctness has ignited controversy across the land. And although the movement arises from the laudable desire to sweep away the debris of racism and sexism and hatred, it replaces old prejudice with new ones. It declares certain topics off-limits, certain expression off-limits, even certain gestures off-limits."