The House has approved a sweeping measure to intervene in the nation’s housing market. The bill would help around 400,000 borrowers refinance their mortgages through government-insured loans. President Bush dropped his opposition to the bill after Democrats agreed to help bail out the nation’s two largest mortgage lenders, Fannie Mae and Freddie Mac. Bush had previously threatened a veto over nearly $4 billion in housing grants to troubled communities. The Senate is expected to take up the measure on Saturday.