The Boston City Council president and city clerk are splitting acting mayor duties this week while Mayor Michelle Wu takes a family vacation in Maine.

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.

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.