Zohran Mamdani may not solve all of the beleaguered US Democrats’ problems, but the surprise front-runner in the race for New York mayor does offer hints on how to win back voters and power. The Democrats – shut out of power in the White House and both chambers of Congress – were seen negatively by 63 per cent of US voters, according to a July poll in The Wall Street Journal, the party’s lowest approval rating in 30 years. John Kane, a professor of political science at New York University, said...