Heisenberg Principle?

Rudolph W. Giuliani, who developed a national reputation for decisive and reassuring leadership after 9/11, now faces the odd challenge of having to reassure some supporters that he can be decisive about a very different issue: running for president.

Even as his fellow Republican John McCain and fellow New Yorker Hillary Rodham Clinton have all but formally declared their candidacies, Mr. Giuliani has proceeded more cautiously.

Rudolph W. Giuliani sounded nearer than ever to being a presidential candidate on Saturday, repeatedly talking about the prospect of running, and inviting voters to judge him by his record as mayor of New York City.... In his first trip since last fall to the state that holds the earliest presidential primary, Mr. Giuliani stepped closer than he has before to suggesting that he will run.