WASHINGTON (Reuters) - U.S. lawmakers working to rein in the country's rising debt said on Monday they will have to make substantial progress this week to ensure the country retains its top-notch credit rating. (http://feeds.feedburner.com/~ff/reuters/topNews?d=yIl2AUoC8zA) (http://feeds.feedburner.com/~ff/reuters/topNews?i=4s8vBSg75PY:ZBcIEjAWAe4:V_sGLiPBpWU) (http://feeds.feedburner.com/~ff/reuters/topNews?i=4s8vBSg75PY:ZBcIEjAWAe4:-BTjWOF_DHI) (http://feeds.feedburner.com/~r/reuters/topNews/~4/4s8vBSg75PY)