Original sentence: Researcher Laird Wilcox give examples of the SPLC's endorsement of Marxism, citing the SPLC's support of left-wing groups having long-time Marxist connections, such as the "Center for Democratic Renewal of Atlanta" and the "Political Research Associates of Somerville, Massachusetts
Edited sentence: Researcher Laird Wilcox give examples of the SPLC's endorsement of Marxism, citing the SPLC's support of extremist leftist groups having long-time Marxist connections, such as the "Center for Democratic Renewal of Atlanta" and the "Political Research Associates of Somerville, Massachusetts