Boston mayoral candidate Josh Kraft backtracked on his campaign promise to implement a rent control plan, saying that he envisions an “opt-in” program that would incentivize landlords to keep rent

Josh Kraft, the son of New England Patriots owner Robert Kraft, formally launched his campaign for mayor of Boston on Tuesday.

With Josh Kraft officially kicking off his campaign to challenge incumbent Mayor Michelle Wu, battle lines are beginning to take shape in Boston's mayoral race.