The White House and Congress, caught unaware by Fidel Castro's illness, prepared Wednesday for a possible showdown in Cuba as lawmakers drafted legislation that would pay millions of dollars to dissidents who fight for democratic change. "The message will be: The United States stands with you," Sen. Bill Nelson, D-Fla., one of the authors, said in an interview. "Be ready to assert your independence." There was no sign of upheaval in Cuba Wednesday, two days after Castro stunned U.S. officials and many of his own countrymen with the news that he had temporarily ceded power to his brother, Raul, in...