Plenty of "daunting challenges" have gone unmet by leaders who "are inevitably summoned  to the fore." For example, there have been "daunting challenges" ever since 1973, and the rise of OPEC, "daunting challenges" that remained entirely unmet by successive American governments and that at first had only to do with the enormous transfer of wealth by oil-consuming nations to oil-producing nations (some ten trillion dollars since 1973), but should have been recognized, at least by the late 1970s, was money that inevitably would go to fund a world-wide Jihad, and that funding included the campaigns of Da'wa, and of a support-system (including mosques and madrasas) for millions of Muslims who have been, over the past thrity or in some cases forty years, to settle deep within Infidel lands, behind what those Muslims have been taught to regard as enemy lines.

And to that has been added the problem, the "daunting challenge" of anthropogenic climate change that is denied, a this point, only by three kinds of people: 1) an handful of gleefully self-conscious "contrarians" of the S. Fred Singer - Lindzen - Lonborg variety, 2) gullible crackpots such as James Imhofe, whose crackpottery takes the unusual form of being "superduper"  skeptics about "scientists" -- in other words, it's a milder manifestation of conspiracy-theorists, only this time the "conspiracy" is by all these crazed leftist scientists, such as james Hansen and Kerry Emanuel and E. O. Wilson, who just want a leftist excuse to damage our truly unsurpassed and unblemished economic system and 3) the attitudinizers, the professional "conservatives" who believe that all those expressing solicitude or worry about poor Mother Nature must surely be 'liberals" with a whole agenda of "liberal" goals.

Giuliani may or may not be just the ticket.  But the idea that "challenges" are always met by  leaders in this country sufficient ot the task -- especially if those people are is a pleasing idea American -- is a pleasing idea, that fits this sentimental age, but one unsupported by the evidence.