(CNN) The blue wave in Pennsylvania will be tinged with a different shade of red in 2018, as four Democratic state house candidates -- all women -- backed by the Democratic Socialists of America won primary races across the state on Tuesday.

On the western front, Summer Lee, an African-American lawyer and community organizer, and activist Sara Innamorato, unseated a pair of longtime Democratic officeholders, cousins Paul and Dom Costa. Both Lee and Innamorato were endorsed by Pittsburgh DSA, one of the organization's most active outposts.

Back east, another pair of candidates, Elizabeth Fiedler and Kristin Seale, won their primaries with the support of Philly DSA. Seale, a first-time candidate and former delegate for Sen. Bernie Sanders at the 2016 Democratic National Convention, will now take on incumbent Republican state Rep. Chris Quinn.

DSA is a leftist political organization that has seen its rank-and-file grow to up to 37,000 dues-paying members, from something like 8,000 since the election of President Donald Trump in November 2016.

The group has become a political and cultural nerve center for a new generation of mostly young activists and progressive organizers. The high-profile victories in Pennsylvania on Tuesday follow what had been DSA's banner win in Virginia last year, when Lee Carter, a DSA member and military veteran, ousted the incumbent GOP majority whip in the state's House of Delegates.

Read More