It’s been dubbed the 'Mamdani effect': support for democratic socialists has been surging since Zoran Mamdani was elected mayor of New York last year.  Now another progressive, Abdul El-Sayed, has defeated a moderate to win Michigan’s Democratic Senate primary. Today, Geoff Kabaservice from the centre-right think tank, the Niskanen Center, on what this shift means for the Democratic Party, and whether the party’s leftward momentum poses a threat to Donald Trump and the Republicans. Featured:  Geoff Kabaservice, Vice President for political studies at the Niskanen Centre