Michelle Wu called on her top challenger Josh Kraft to release his tax returns to reveal any financial interests or business “entanglements” he may have with the city that could impede his ability

Robert Kraft’s son, Josh Kraft, has left the Patriots franchise as he zeroes in on the Boston mayoral race, where early polling shows he’s trailing substantially to incumbent Michelle Wu. Josh, 58, is trailing Wu in the polls, 59-29 percent, ahead of this November’s election cycle. They are running as Democrats.

The poll of 500 Boston voters likely to participate in the Sept. 9 preliminary election showed a wide gulf between Wu and Kraft, who drew 30 percent support to her 60 percent.