WASHINGTON — Less than two years after passing major legislation aimed at reforming the government’s much-criticized flood insurance program, Congress on Thursday sent President Barack Obama a bill to scale back many of the resulting big flood insurance premium increases faced by hundreds of thousands of homeowners. The measure would also allow below-market insurance rates to be passed on to people buying homes with taxpayer-subsidized policies.

The measure breezed through the Senate and on to Obama’s desk by a 72-22 vote. The House passed the measure last week.

The legislation significantly rewrites a major overhaul of the flood insurance program that passed almost unanimously in 2012. Those 2012 changes were aimed at weaning hundreds of thousands of homeowners off of subsidized rates and required extensive updating of the flood maps used to set premiums. But its implementation has stirred anxiety among many homeowners along the Atlantic and Gulf coasts and in flood plains, many of whom are threatened with unaffordable rate increases.

Sen. Mary Landrieu, D-La., said the White House has indicated Obama will sign the measure into law despite earlier administration reservations about a Senate-passed bill that would have delayed implementation of the 2012 law.

“While it is important to put this program on sound financial footing, middle-class families should be able to afford the insurance they need to stay in their homes,” White House spokesman Bobby Whithorne said.

Thursday’s bill was written by House Majority Leader Eric Cantor, R-Va., and Rep. Michael Grimm, R-N.Y., with input from Democrats like Rep. Maxine Waters of California, whose votes were critical to House passage last week.

The bill would repeal a provision in the 2012 law that threatens hundreds of thousands of homeowners with huge premium increases under new and updated government flood maps.

Their properties were originally built to code but were subsequently found to be at greater flood risk. Such “grandfathered” homeowners currently benefit from below-market rates that are subsidized by other policyholders, and the new legislation would preserve that status and cap premium increases at 18 percent a year. The 2012 reforms required premiums increases to actuarially sound rates over five years.