WASHINGTON, Oct. 16 — On an overcast Friday morning last month, White House aides ushered an influential group of conservative radio hosts into the Oval Office for a private audience with the president. For an hour and a half, Mr. Bush discussed his case for the war in Iraq, his immigration proposals and even the personality of his Scottish terrier Barney, who scratched on the door during the session until the president relented and let him into the office, according to several hosts who attended. The meeting, which was not announced on the president’s public schedule, was part of an...