I agree that the Kitty debate question was a big moment but I don’t think it cost Dukakis the election. In the polls Dukakis went from 49 to 42 immediately after the debate but that is only a snap shot.

Here is an excerpt from “In God we trust”:

During the 1988 primary and elections, the Times Mirror Corporation, publishers of the LATimes, using factor analytic techniques, developed a sophisticated method to measuring ten independent sectors of the electorate. The sector they identified as “moralist” is a purer measure of the conservative religious community than the measures “fundamentalists” or “evangelicals” used by most pollsters. In the last Times Mirror poll conducted before the general election, the moralists favored Bush over Dukakis by a margin of 93 percent to 3 percent (Times Mirror 1988). Furthermore, George Gallup, who conducted the polling for Times Mirror, reported that while the moralists constituted 12 percent of the electorate, they were expected to represent 14 percent of all voters (Gallup 1988).

Bush’s solid sweep of the South and Southwest, where evangelical Christians concentration is the greatest, was impressive and the margin of victory can substantially be attributed to the evangelical vote. Albert Menendez (1988) an authority on religion and voting has been reluctant to acknowledge that the New Christian Right has ever had any political clout, concluded that the evangelical vote was also probably the margin of victory for Bush in the tightly contested states of Pennsylvania, Illinois, and Missouri. Menendez reported, for example, that seventeen strongly evangelical counties in Pennsylvania delivered a 134,000 plurality for Bush to offset a Dukakis margin of 34,000 for the rest of the state. And in a sample of campus precincts of ten evangelical colleges, Menendez reported that Bush did almost as well as did Reagan in 1984 (84 percent to 86 percent).