NEW YORK (Reuters) - IMF chief Christine Lagarde on Tuesday urged the United States to quickly resolve a political stalemate over raising the debt ceiling, warning that failure to reach an agreement would have serious consequences for the world economy. (http://feeds.feedburner.com/~ff/reuters/topNews?d=yIl2AUoC8zA) (http://feeds.feedburner.com/~ff/reuters/topNews?i=t9d93dN3Ezw:oEVHwadt_s0:V_sGLiPBpWU) (http://feeds.feedburner.com/~ff/reuters/topNews?i=t9d93dN3Ezw:oEVHwadt_s0:-BTjWOF_DHI) (http://feeds.feedburner.com/~r/reuters/topNews/~4/t9d93dN3Ezw)