City Councilor Michell Wu, left, and Acting Mayor Kim Janey, right. Photos courtesy of Michelle Wu and Boston mayor's office.

Boston’s Acting Mayor Kim Janey and At-Large City Councilor Michelle Wu lead a new poll from Suffolk University and the Boston Globe taking the temperature of the city’s race for mayor.

Voters will head to the polls Sept. 14 for the preliminary election, which will narrow the wide field of candidates down to two who will go head-to-head in the Nov. 2 general election.

With 21.6 percent of the 500 likely voters polled over the phone in English and Spanish by Suffolk between June 23 and June 26 still undecided, it’s clear that the race is starting to tighten but many voters haven’t yet made up their minds.

Wu lead all six major candidates in the race with support from 23.4 percent of respondents saying she was their first choice, while Janey came in second with 21.6 percent support followed by At-Large City Councilor Annissa Essaibi George with 14.4 percent, District 4 City Councilor Andrea Campbell with 10.8 percent, state Rep. Jon Santiago with 4.6 percent and former city economic development director John Barros with 1.8 percent.

The poll’s margin of error was 4.4 percent, putting Janey and Wu in a statistical tie.

Wu and Janey also came out of the Suffolk poll with the highest favorability ratings – 61.8 percent for Wu and 57.6 for Janey.

The poll also asked residents what the city’s next mayor should do to make housing more affordable in the city.

The largest share, 48.2 percent, said the city should “focus on developing affordable housing even if that means less housing overall,” while 17.6 percent said the city needed to “accelerate the building of new housing at all price points.” Another 13.2 percent said the city should try to maintain the pace of development achieved by former Mayor Marty Walsh, while another 13.2 percent said the city needed to slow down new development.