WASHINGTON — Treasury Secretary Henry Paulson said Tuesday the administration was exploring what would be a significant expansion of the program to help at-risk mortgage holders.

Paulson, in an interview on CNBC, said the administration was involved in discussions with the mortgage industry to expand a current program to freeze adjustable rate mortgages for five years to include borrowers of loans at prime rates. Currently, the rate freeze only covers a much smaller segment of adjustable rate loans, those made to subprime borrowers. Those are borrowers with weak credit histories.

"One thing we will consider with the HOPE NOW alliance is ... maybe expanding this beyond subprime borrowers to other borrowers," Paulson said in the CNBC interview.

Paulson did not provide any details on when this expansion might go forward. The HOPE NOW alliance is a coalition of mortgage industry companies which are seeking to reach at-risk borrowers to help them avoid foreclosures.

The administration last month unveiled its most significant move to date to deal with the mortgage crisis when it brokered an agreement with the mortgage industry to freeze rates on certain subprime mortgages for five years in an effort to help homeowners in danger of losing their homes when their lower introductory rates reset to sharply higher levels in the coming two years.

There are 1.8 million subprime mortgages that are scheduled to reset to higher rates this year and in 2009.

Paulson in the CNBC interview also called on Congress to quickly pass pending legislation that would reform the Federal Housing Administration, which he said would help 250,000 at-risk homeowners who have adjustable rate subprime mortgages refinance to more affordable loans and another piece of legislation that would expand the availability of so-called "jumbo" mortgages, loans higher than $417,000.

The two giant government-sponsored mortgage companies, Fannie Mae and Freddie Mac, cannot presently back these jumbo loans, which restricts their availability.

On Monday, Paulson had said in a speech in New York that the current housing correction was "inevitable and necessary" following five years of an unsustainable boom which saw sales and home prices hit record levels.