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

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.

With the city’s preliminary election closing in, Boston Mayor Michelle Wu holds a nearly 30-point lead over her nearest challenger, according to a new poll. Wu leads philanthropist and community activist Josh Kraft 59%-29% in the new Boston Globe/Suffolk University poll out Monday.