WASHINGTON The United States and Colombia have called home their respective envoys in an apparent acceleration of worsening ties, against the backdrop of an alleged plot against Colombia's leftist leader. Washington went first, recalling its charge d'affaires John McNamara "following baseless and reprehensible statements from the highest levels of the Government of Colombia," State Department spokeswoman Tammy Bruce said, without giving specifics. Within hours, Colombian President Gustavo Petro