New cities are joining the effort to head off home foreclosures by using a twist on the power of eminent domain, despite threats of financial retaliation from Wall Street and Washington.

On Saturday, Mayor Wayne Smith of Irvington, N.J., will announce that his mostly working-class city is proceeding with a legal study of the plan. Irvington could try to head off legal action and repercussions through what are called “friendly condemnations,” in which incentives are used to persuade the owner to drop any objections, he said. “We figure if this program works it can help anywhere from 500 to 1,000 homes.”

This summer the similarly working-class city of Richmond, Calif., in a heavily industrial part of the San Francisco Bay Area, became the first to identify homes worth far less than their owners owe, and offer to buy not the houses themselves, but the mortgages. The city intends to reduce the debt on those mortgages, saying that will prevent foreclosure, blight and falling property values. If the owners of the mortgages — mostly banks and investors — balk, the letters said, the city could use eminent domain to condemn and buy them.

Since then, intense pressure from Wall Street and real estate interests, including warnings that mortgages will become difficult or impossible for Richmond residents to get, has whittled away support for the plan. The city has yet to actually use its power of eminent domain, but it is already fighting two lawsuits filed in federal courts.