Boston Mayor Michelle Wu is kicking off her campaign for re-election with a strong lead over her opponent Josh Kraft, according to an Emerson College poll released Thursday.

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 survey offers the first early look at the matchup between the first-term progressive mayor and her most prominent challenger.

Boston’s largest police officers' union will endorse incumbent Mayor Michelle Wu for reelection on Thursday afternoon, its leadership said. The Boston Police Patrolmen’s Association said its members voted “overwhelmingly” to support Wu at the union’s most recent monthly meeting.

Boston mayoral candidate Josh Kraft says public records show the city’s bid process for the White Stadium pro soccer rehab project was “rigged” and is calling for an investigation into whether Mayor Michelle Wu violated procurement laws.