The United States lost its top-notch credit status after Standard and Poor's lowered it from AAA to AA+, but the U.S. could get it back, though perhaps not in the short-run.

Even after Friday's downgrade, the ratings agency's outlook for U.S. credit-worthiness is negative, and the U.S. has a one in three chance of losing another notch on the ranking scale.

"That means that we think the risks currently or the rating are to the downside," David Beers, global head of S&P's government debt rating unit, told "Fox News Sunday."

The S&P will monitor the U.S. for about six to 24 months to see whether its fiscal position deteriorates further or if political gridlock gets worse. John Chambers, the group's managing director, said Sunday it would take stabilization of the debt as a share of the economy to determine the direction of S&P's rating, and it's no easy task to get it to rise. 

"If history is a guide, it could take a while. We've had five governments that lost their AAA that got it back. The amount of time that it took for those five range from nine years to 18 years," he told ABC's "This Week."

Chambers said the group uses a set of criteria built on five pillars: politics, the actual economy, fiscal and monetary policy and externalities. He said the same pillars apply to all 126 governments the group rates. 

"I think as time passes, people will come to see that the United States' credit standing is really not quite the same level as -- as the ones that we rate AAA," he said.