"While we intend to urge our colleagues to take further action, it unfortunately appears unlikely that Congress will do so."
Chinese, European and Russian financial leaders this week criticized the Fed's move, saying it could depress the dollar's value and create a ripple through the global economy.
President Obama defended the move, arguing that a strong U.S. economy is crucial to a global recovery.
"We support Secretary Geithner in his efforts, including at this weekend’s G-20 meetings, to encourage our trading partners in Europe, Asia, and South America to take these steps," they said.
"The 2008 financial crisis and the ensuing recession have left us with no choice but to deploy, as aggressively as possible, all of the tools that we possess."