Maryland’s senior senator endorsed progressive candidate Abdul El-Sayed in Michigan’s Aug. 4 Democratic Senate primary, breaking with Senate Democratic Leader Chuck Schumer (D-N.Y.), who is backing Rep. Haley Stevens (D-Mich.). Sen. Chris Van Hollen (D-Md.), who shared the endorsement first with The Associated Press as early voting opened in Michigan on June 25, is the first senator to back El-Sayed since Sen. Bernie Sanders (I-Vt.) did so shortly after his campaign launched last year. The endorsement landed days after progressive challengers ousted two House Democratic incumbents in New York and following a primary in Maine earlier this month where Schumer had backed Gov. Janet Mills before she suspended her campaign and progressive Graham Platner won the nomination....