Former New York City mayor Rudy Giuliani is the most popular politician in the United States, according to a national poll this week testing support for potential candidates in the 2008 presidential race. The survey of some 1,900 voters by the Quinnipiac Polling Institute asked respondents to rate several nationally known politicians on a scale from 0 to 100, with higher numbers reflecting higher regard. Giuliani topped the list, with an average score of 63.5 percent, followed by Democratic Senator Barack Obama, seen as one of his party's rising stars. Obama scored 59.9. In third place was maverick veteran Republican...