text:  Live from NPR News in Washington, I'm Lakshmi Singh. Former President Donald Trump says he will announce his choice for vice president on the opening day of the Republican National Convention. Thousands of Republicans were expected to descend on downtown Milwaukee this week for the highly anticipated event. NPR's Ximena Bustilla reports the Trump campaign has been retooling its message two days after an attempted assassination at a Pennsylvania rally injured Trump and others and claimed one life.