Mark Zandi, the chief economist of Moody's Analytics and a frequent face before Congress in matters of the economy, sees the U.S. recovery on track, but he warns of four possible disruptors.

Zandi tells NPR that he is sticking by his prediction of a recovery by the end of this year, and that he believes that jobs and housing will improve over 2011.

However, Zandi says, watch housing, Europe, China, and state and local debt problems.

To begin with, housing prices continue to fall, which Zandi says “makes me nervous." The huge backlog of foreclosures continues to weigh on the construction sector, which is a big piece of the U.S. economic puzzle.

Secondly, Zandi says European leaders must act faster to save countries on the brink, even if it means “kicking the can down the road” for three of four years. By then, he says, their economies will be in better shape to tackle debt.

A third issue is Chinese inflation. A faster-rising yuan would offset the problem of rising prices there, but it would also slow exports and hurt their economy, Zandi says. A China crash would be very bad for the world, he maintains.

Finally, state and local governments are in serious debt trouble. While the chance of a series of “small” municipal defaults would be worrying, Zandi doesn’t believe we will see any state defaults, suggesting that fears of massive muni bond defaults are overdone.

Meredith Whitney, the former Oppenheimer & Co. banking analyst who correctly called the original credit crisis and has since created her own firm, is under fire for her repeated assertion that up to 100 “sizeable” defaults await U.S. state and local government bondholders.

“There’s not a doubt in my mind that you will see a spate of municipal-bond defaults,” Whitney told the “60 Minutes” program in December.

“This will amount to hundreds of billions of dollars’ worth of defaults,” she said then.