In the U.S., POD can be no Progressive Era, which means the Gilded Age goes on indefinitely with its unregulated capitalism into the 1920s.
The Labor movement becomes too strong to suppress, to the point of a marxist Labor Party becoming the second largest party after the Republicans, but not strong enough to actually win the Presidency. Then the Great Depression hits and it's much worse, the Labor party wins, but the establishment is too scared of them and plots to coup them out of power. Coup succeeds, but public response turns massively against the coupers and in favor of Labor, one thing leds to the other.
This also just happens to be how Reds! does it.
But actually you could just have the marxist party be so utterly dominant after the Great Depression that they're able to carry out a radical programme of transformation and the abolition of capitalism.