WASHINGTON — Homeowners stuck with costly mortgages and facing foreclosure will be able to refinance into more affordable loans with the assistance of the Federal Housing Authority under the HOPE for Homeowners program that took effect Wednesday.

“The turbulent economy has reached a boiling point, and the American people require and deserve immediate relief,” Maine Republican Sen. Olympia Snowe said in a statement. “With these programs, homeowners can access FHA-insured mortgages or receive valuable tax credits for first-time buyers. I encourage Americans to take advantage of these beneficial provisions and contact the FHA today.”

The HOPE for Homeowners program is authorized to insure up to $300 billion in mortgages and is expected to serve approximately 400,000 homeowners over the next three years.

“HOPE for Homeowners will add to the Housing and Urban Development Department’s existing efforts to make FHA refinancing available to homeowners who need it most,” FHA Commissioner Brian D. Montgomery said in a statement.

“One year ago, FHA expanded refinancing into its FHA Secure program. Since that time, we have helped more than 360,000 families keep their homes by refinancing with FHA, and we will assist a total of 500,000 families by the end of this year.”

The temporary and voluntary program is intended to create new equity for troubled homeowners to ensure affordability and sustainable homeownership. Participating borrowers will have to take out 30-year FHA loans for 90 percent of the current value of their home and share their newly created equity and future appreciation equally with the FHA, according to the agency.

Kristine Foye, a spokeswoman at the New England Region of HUD, said, “The program is really designed to help people stay in their homes.”

To benefit from the proceeds of the loans refinanced with government insurance, investors and lenders have to agree to take substantial and significant losses, which would be less than the losses associated with foreclosure, according to the FHA.

“Anybody who is interested in it will need to contact their lender, to work with their lender being able to write down their existing mortgage,” Foye said.

According to the FHA, only owner-occupants who are unable to afford their current mortgage payments are eligible for the program. Qualified borrowers’ existing mortgages must have been originated on or before Jan. 1, 2008, and at least six payments must have been made.

The borrowers’ mortgage debt-to-income ratio must be at least 31 percent. The borrowers also need to prove that they cannot afford their current loan payments and did not intentionally miss any payments and that they own only one home.