Pressures on the city’s middle class could be a major theme in the next mayoral election, as four potential candidates to replace Mayor Bloomberg pushed the urgent need to address the issue during a forum yesterday.

Middle-income families are being both pushed out and repelled by the city’s high housing prices, the politicians, Rep. Anthony Weiner, Comptroller William Thompson Jr., Council Member John Liu, and the president of the Bronx, Adolfo Carrion Jr., said at an event hosted by the Drum Major Institute and Baruch College. As a result, they said, the city is becoming a home for just the rich and the poor.

The forum was held in part as a response to a study by the Brookings Institute last summer that found New York City had the smallest proportion of middleclass families of 100 major cities in 2000, comprising 16.2% of the city’s population. New York had near-equal percentages of highand low-income families, according to the study, which defined middle class as then making between about $35,000 and $55,000.

The politicians catalogued a wide array of factors that push and pull middle class families from the city. Joined by other speakers including Governor Cuomo, each declared the need for broad-based change through education, health care, and tax changes, as opposed to one or two quick-fix solutions.

Mr. Weiner pushed the option of a municipal solution to bring affordable health care for many families that do not qualify for government programs. “We do need to think of this as a New York City problem, and not a state problem, and not a federal problem,” he said.

Mr. Weiner sparred with Mr. Liu, who pinned the responsibility for broader health care access on the state or federal governments. Given the high financial times presently enjoyed by the city, Mr. Liu called for tax cuts.

“When we have surplus times, we do have to roll back the rates,” he said.

The forum comes at a time when high housing prices are a perennial topic at dinner tables and community board meetings throughout the city. A professor of public affairs at Baruch College, Douglas Muzzio, said in an interview that a discussion of the shrinking middle class “has to be” a major issue in the 2009 mayoral race.

“When we talk about the middle class, it is at the nexus of all the important issues,” Mr. Muzzio said, adding that a declining proportion of service and other workers could be destabilizing.