A negative outlook is a sign the rating may be downgraded in 12 to 18 months. McConnell's plan, which is being negotiated with Senate Majority Leader Harry Reid, would include about $1.5 trillion in deficit-reduction measures. Hess said a "much larger amount" of deficit-reduction measures would be necessary for Moody's to affirm U.S. ratings with a stable outlook. In the most recent development in Washington on Tuesday, President Barack Obama supported efforts by a bipartisan group of U.S. senators with a more ambitious budget plan that includes $3.75 trillion in savings over 10 years. Asked about the ideal size of the deficit-reduction measures, Hess said $4 trillion "could lead us to affirm the rating at Aaa with a stable outlook, if those measures were actually adopted." "I'd rather not opine on the numbers in between," he said, also noting that Moody's does not have a view on whether that deficit reduction should be achieved via revenue increase or spending cuts.