Democratic candidates around the country now seek their blessing. Americans are joining their ranks by the thousands, rapidly expanding the group’s membership rolls in just a few years.

And a sharply leftist political agenda that once produced eye rolls – on everything from their opposition to capitalism to their questioning the very existence of prisons – has become a serious topic of discussion on social media, and in mainstream political debate.

In short, it’s going according to a plan by the Democratic Socialists of America, a group that’s dedicated to pushing an anti-capitalist, socialist platform by infiltrating and working within the Democratic Party, and pushing it further and further to the left.

“Progressive and socialist candidates who openly reject the neoliberal mainstream Democratic agenda may choose for pragmatic reasons to use the Democratic Party ballot line in partisan races,” wrote Joseph M. Schwartz, vice chairman of the DSA, in the socialist Jacobin Magazine last August. “But whatever ballot line the movement chooses to use, we must always be working to increase the independent power of labor and the left.”…