(RECAP: Leading economists are voicing growing concern about the flagging U.S. housing recovery, raising doubts about a key pillar of economic growth. Federal Reserve Chair Janet Yellen, told Congress Wednesday that the recent housing slowdown “could prove more protracted” than expected. More than half of 40 top economists surveyed by USA TODAY May 2-6 are more pessimistic about the housing recovery than they were in December. Neither Yellen nor the surveyed economists expect a housing rebound that began in 2011 to reverse course. Rather, economists say the turnaround will likely be more gradual, crimping economic gains in 2014.)