All 12 Democrats on the Senate Banking Committee urged the Federal Housing Finance Agency to remove even more restrictions to refinancing Fannie Mae and Freddie Mac mortgages.

The FHFA eased several rules last November under a revamped Home Affordable Refinancing Program. It lifted the loan-to-value cap, certain appraisal requirements and upfront loan-level price adjustment fees and removed some representation-and-warranty risk if the borrower refinances with the same lender.

In a letter sent Friday, the lawmakers suggested doing even more. They cited suggestions in a recent Federal Reserve white paper that would remove the remaining upfront fees where Fannie and Freddie already hold the credit risk.

They asked the FHFA to make it easier for borrowers with more than 20% equity in their home to refinance.

Lawmakers also asked to reduce more rep and warranty risk "in order to remove disincentives for servicers to refinance."

"We appreciate your commitment to fully implement recent changes to HARP, but we believe there is more you can do today," the letter reads. "Our constituents and responsible homeowners can no longer wait, and as elected officials responsible for oversight of your agency, neither can we."

Roughly 2,700 mortgages with a loan-to-value ratio between 105% and 125% received a HARP refinancing in December, nearly half of the 5,100 such loans refinanced in November, according to FHFA data.

More than 20,600 mortgages with LTVs between 80% and 125% LTV received a HARP refi, which was also down 31% from the month before, according to the FHFA.

Meanwhile, mortgage rates dipped back below 4% last week, according to Freddie Mac.