Europe's persistent debt crisis is likely to "tumble along" for an extended period of time but not have much effect on the U.S., St. Louis Federal Reserve President James Bullard told CNBC.

James Bullard

Rather than explode and cause global contagion, the problems countries such as Greece and Italy have repaying their sovereign debt probably will be contained, said Bullard, who believes the Fed has sufficient policies in place to safeguard the American economy.