Rove postulated that Bush, like McKinley, had arrived at a moment when the old politics no longer applied and the new had yet to be formed. By offering himself as a pro-immigrant, pro-growth, "compassionate" conservative, he would attract the new voters of the day, including Hispanic immigrants, as well as workers in the postindustrial economy, while at the same time mobilizing the party's conservative Christian base. He would be the candidate of growth and the future while casting his rival, Al Gore, as the embodiment of an exhausted big-government credo. And this strategy worked: in 2000, Bush made gains among Hispanics and carried 97 of the country's 100 fastest-growing counties. Of course, Gore won the popular vote and, by some accounts, the election. And yet since that time, the Democrats have come to look like the party of the underprivileged and the highly educated and scarcely anyone else.

Image Mark Hanna, the Karl Rove of his day, with McKinley firmly in hand. Credit... The Granger Collection

So why doesn't 2006 recall the G.O.P.'s glory years? First of all, McKinley was facing a particularly hapless generation of Democrats. A long period of deadlock had come to an end in the off-year election of 1894, when the failure of the incumbent Democrats to stem a financial panic led to a colossal electoral rout. In a shambles, the party took a decisive turn to the left in 1896 by choosing the populist Bryan, who ran again in 1900 and 1908. Today's Democrats are much closer to the mainstream, and the realignment has been correspondingly shallower. Over the last decade, as the political analyst Michael Barone observes, the national vote for president and for Congress has divided almost down the middle. Second, while McKinley had the good fortune to arrive at the dawn of a new era, Bush came along three decades after Republicans broke into the Democrats' solid South to establish a new majority. The historic tide may have already been ebbing.

And finally, George W. Bush is no William McKinley. The figure we meet in the biography by Lewis Gould, McKinley's great champion and Rove's teacher at the University of Texas, is a canny political veteran, more pragmatist than dogmatist. McKinley governed from the center the Democrats began to vacate in the Bryan era. The president not only made a show of mingling with workers but also appointed labor leaders to his cabinet and publicly supported the call for an eight-hour day for government employees. And for all his reputation as an imperialist who provoked a war with Spain, McKinley appears to have held out as long as he could against the rabid jingoism of the public and Congress, especially after the sinking of the Maine in Havana's harbor in February 1898. "What is remarkable," Gould concludes after reviewing the evidence, "is how long the president was able to obtain time for the conducting of peaceful diplomacy."

George W. Bush is, by contrast, a radical figure, a profoundly self-confident leader willing to stake all on his unshakable inner convictions — which is to say that this president made himself a hostage to fortune in a way that the coldly calculating McKinley never would have done. Thanks in no small part to the supreme self-assurance, the disdain for more cautious points of view, of the president and his inner circle, the administration has run aground on Iraq.

The war in Iraq is the biggest, but not the only, reason for the growing crisis. It is instructive that only one-third of mainline Protestants now say they approve of President Bush's performance (as opposed to one-half two years ago), according to a recent poll by the Pew Research Center for the People and the Press. A Congress that spends days arguing over the body of Terry Schiavo or the merits of a constitutional amendment to prohibit same-sex marriage does not feel like the embodiment of the future to more moderate or more secular Republicans. Rove and Bush have driven an already conservative party to the right. "The McKinley party was still plausibly the party of Lincoln," as the historian Sean Wilentz observes. "But Bush and Rove are the culmination of 30 years of realignment in which the Republicans became the party of the South the way the Democrats were in McKinley's day."