Even before Thursday night's Fox News debate, there was talk that Cruz might have "peaked too early" in Iowa. Cruz narrowly led the Donald in the typically very accurate and influential Des Moines Register/Bloomberg poll released on January 13. But since then the polling has shown slippage for Cruz, generally attributed to a combo attack from Trump on Cruz's Canadian birth and from the Branstad family (Terry, the six-term governor, and son Eric, the ethanol lobbyist) on his opposition to special treatment of the corn-based alternative fuel by the federal government. Even more ominously, third-place candidate Marco Rubio, the favorite...