Arizona Sen. John McCain, who blamed illegal immigration Monday for Republican losses in major congressional races, has rejected Hazleton Mayor Lou Barletta’s invitation to discuss the issue. “Sen. McCain truly appreciates your invitation and the valuable opportunity it represents,” Jo Black, a scheduling official in the presumptive Republican nominee’s presidential campaign, wrote in a letter to Barletta’s congressional campaign Wednesday. The letter cited “tremendous demands” on McCain’s time and a “large volume of similar requests.” Efforts to reach McCain’s campaign were unsuccessful. Last week, Barletta invited McCain and the Democratic presidential candidates, Sens. Hillary Clinton and Barack Obama, to come...