WASHINGTON — Rescue legislation sailed through the House yesterday aimed at helping 400,000 strapped homeowners avoid foreclosure and preventing the collapse of troubled mortgage companies Fannie Mae and Freddie Mac.

The 272-152 vote reflected a congressional push to send election-year help to struggling borrowers and to reassure jittery financial markets about the health of two pillars of the mortgage market.

Hours before the vote, President Bush dropped his opposition to the measure, which now is on track to pass the Senate and become law within days.

The White House swallowed its distaste for $3.9 billion in grants for devastated neighborhoods. In return, the administration got both the power to throw Fannie Mae and Freddie Mac a lifeline and the legislation Republicans long have advocated to rein in the government-sponsored mortgage companies.

Treasury Secretary Paulson and lawmakers in both parties negotiated the final deal.

It accomplishes several Democratic priorities, including aid for homeowners, a permanent affordable housing fund financed by the two mortgage companies, and the money for hard-hit neighborhoods. The grants are for buying and fixing up foreclosed properties.

“It is the product of a very significant set of compromises,” the chairman of the House Financial Services Committee, Rep. Barney Frank, said. “We are dealing with the consequences of bad decisions and inaction and malfeasance from years before,” Mr. Frank, a Massachusetts Democrat, said.

Mr. Paulson said he would push for enactment of the bill by week’s end. Despite disappointment with some items rejected, he said “portions of this bill are orders of magnitude more important to turning the corner on the housing correction and supporting our markets and our economy.”

Mr. Bush had argued the neighborhood grants would benefit bankers and lenders. But the White House said a showdown with Congress over the proposal would be ill-timed.