The step was the first change by the bank since August 2005, when it cut the rate to 4.5 percent.
"It has been a difficult three years for our members," whose wages were cut 12 to 13 percent.
The base rate itself was recently cut to 12.5 percent.
For two years, interest rates can be cut to 5 percent, almost half current levels.
Such a move, they said, could cut the increase to 3.5 percent.
If Republicans cut that to 70 or 75 percent, it could turn some elections.
The top tax rate on dividends has been cut to 15 percent, too.
He must also press Congress to cut the capital gains tax to 15 percent.
Under the new deal, it will cut that to 25 percent.
So far, they have cut interest rates slightly, to 4.5 percent.