As one cabinet secretary proposed regulatory changes to recover from the bursting of a housing-market bubble, the cabinet member responsible for housing policy said he would step down to "attend more diligently to personal and family matters."

Housing and Urban Development Secretary Alphonso Jackson told President Bush he would step down April 18.

Jackson announced his decision 10 days after two senior Democrats in the Senate—Christopher Dodd of Connecticut and Patty Murray of Washington—called for Jackson's resignation.

They told the White House that Jackson could no longer effectively lead the agency because he had refused to answer questions about whether he tried to help a business friend obtain some valuable government-owned property.

The allegation came in a federal lawsuit filed by the Philadelphia Housing Authority. The lawsuit alleges that Jackson injected himself into a dispute between the housing authority and property developer Kenny Gamble.

At one point, the lawsuit alleges, Jackson's assistant secretaries warned that H.U.D. would find the housing authority in violation of a federal contract if it didn't give the property, valued at $2 million, to Gamble.

After the housing authority's director, Carl R. Greene, refused, H.U.D. found the city agency in violation of a separate, larger agreement and took steps to withdraw $50 million in federal funds.

H.U.D. officials have said they were not pressing a deal on Gamble's behalf, just trying to get the city to accelerate a long-delayed housing project. But when Congress started to look into the matter, Jackson declined to discuss what role, if any, he'd played in it.

Earlier, The New York Times reported that authorities were investigating allegations that Jackson had steered other federal contracts—involving the Virgin Islands housing authority and post-Hurricane Katrina rebuilding work—to friends. H.U.D. officials declined to comment on those allegations.

Jackson announced his plan to retire as Treasury Secretary Henry Paulson was outlining an overhaul of how the government regulates financial institutions. The plan is in response to the effects of the mortgage-market meltdown that has already claimed one bank, Bear Stearns, and cost billions of losses at others.