The US Capitol Building is pictured at dusk in Washington, DC, on July 29, 2011. Spurred on by President Barack Obama, US lawmakers set the stage late Friday for a frantic beat-the-clock weekend effort to avert a catastrophic debt default sure to rattle the world economy. In a grim warning of what may come if there is no breakthrough by Tuesday's deadline, US markets tumbled for a fifth straight day -- a month of gains wiped out in a week of losses due to poor US growth and the political stalemate. AFP Photo/Jewel Samad (Photo credit should read JEWEL SAMAD/AFP/Getty Images)
