A Fitch Ratings executive said Thursday that the firm would likely downgrade US debt if the federal government does not get its fiscal house in order.

Speaking at the firm's global banking conference in New York, Fitch sovereign group managing director Ed Parker said "the US does not have a credible fiscal consolidation plan" and that "if we don't see one after the election, I would expect a downgrade."

Fitch rates the US at triple-A but put it on negative outlook earlier this year, and Parker's comments were a reiteration of the firm's position. Fitch has the US, UK and France on negative outlook because of high debt-to-gross-domestic-product-ratios.

Parker noted that the three countries, plus Germany, have the top credit ratings but are also the most heavily indebted nations.

"There is a limit to how high these government debt levels can go," Parker said.

Regarding the future of the eurozone, Parker said that in the event of a Greek exit from the eurozone, all member countries in the union would be put on negative ratings watch and placed under review. He also said that the peripheral countries of Italy, Spain, Ireland, Portugal and Cyprus, all currently on negative outlook, would be downgraded.

"The big concern is potential contagion to other countries," Parker said.

He added that the most likely outcome for Europe is to "muddle through" its financial crisis, rather than take definitive action in any direction. A break-up of the eurozone would be "financially and politically costly," and even if Greece were to exit "there's no blueprint for that to happen," he said.

Copyright (c) 2012 Dow Jones & Company Inc.