Released: February 26, 2007 Hillary Holds On; Giuliani Expands Lead in National Primary Tests Obama advances, but McCain fades in partisan contests; Obama, Giuliani do best in general election match-ups New York Sen. Hillary Clinton clings to a shrinking lead over Illinois Senator Barack Obama in a national test of Democratic primary voter preference, while Republican Rudy Giuliani is expanding his edge over John McCain, the maverick senator from Arizona, a new Zogby International telephone poll shows. The survey was the first since last week’s very public spat between the Clinton and Obama campaigns over Hollywood fund–raising and the conduct...