By Donna Smith WASHINGTON (Reuters) - Soaring healthcare costs have been blamed for the grim U.S. budget deficit, which two government reports on Tuesday said could push the national debt to $20 trillion in the next 10 years. Congress is now grappling with President Barack Obama's plan to overhaul the $1 trillion U.S. healthcare system, which Republicans say is too aggressive but which many Democrats say is indispensable.