New York Mayor Zohran Mamdani is being touted as an “undeniable power broker” after his slate of radical socialist endorsees won in state and national races on Tuesday night. This might seem like good news for Republicans, since it can make the national Democrats look extreme. But the broadcast networks have a serious problem finding anyone too extreme on the left. The Democrats will try to absorb these radicals and cater to them, and it’s alrea…