Michelle Wu holds a double-digit lead over philanthropist Josh Kraft in the race for Boston mayor, a new poll from Emerson College finds. The preliminary election to narrow the field down to two candidates is in September. The poll asked more than 600 registered voters who they would vote for if the election were held today.

Boston Mayor Michelle Wu will find herself testifying before a Congressional committee Wednesday with a hostile Republican majority intent on grilling her and three other Democratic mayors on their limited cooperation with federal immigration enforcement.

The endorsement is the first time in more than 30 years that the city's largest police union has supported a Boston mayor for reelection, the union said.