IF THE LAST 180 YEARS of American politics are any guide, the 2004 election will see one of the two major parties become dominant in presidential politics for 36 years.

If that seems a bit deterministic, consider these facts. In 1824, Andrew Jackson won a strong plurality in the popular vote and in the Electoral College. Though Jackson was denied the presidency by the House of Representatives, his showing was the harbinger of a 36-year period in which the mass-based Democratic party he and his followers fashioned lost only two subsequent presidential races.

In 1860, Abraham Lincoln became the first Republican president. In the subsequent 36 years, Grover Cleveland's two non-consecutive terms were the only exceptions to Republican control of the White House.

In 1896, rural-based populist forces led by William Jennings Bryan crushed Cleveland's followers at the national convention and took over the Democratic party. Republican nominee William McKinley took advantage of the rupture, scoring a breakthrough in the rapidly growing cities of the Northeast and Midwest. For 36 years, only Woodrow Wilson's two terms interrupted a GOP hegemony significantly more one-sided than the regionally based Civil War alignment of 1860-96.

In 1932, Franklin Roosevelt scored a colossal landslide, which inaugurated the New Deal era. In the subsequent 36 years, Republicans held the presidency for only the two terms of war hero Dwight Eisenhower.

In 1968, the upheavals of the 1960s shattered the New Deal coalition and made Richard Nixon president. Even though Nixon's was a failed presidency and Democrats retained predominance in Congress until

If there is one reason why 2004 may not see a realignment, it is, paradoxically, the strong political hand enjoyed by President Bush in the wake of the surprising GOP gains of 2002. The pattern of strong presidents seeking reelection is that they tend not to risk running on the kind of defining issues that make for realignments. In fact, a long-term partisan realignment has never been triggered by a sitting president successfully seeking reelection.

Recent presidents who won their second election--Eisenhower, Nixon, Reagan, and Clinton--started ahead, or pulled ahead early in the cycle, and played not to lose. They largely avoided mistakes and won handily, but provided little in the way of coattails to their party. Remarkably, the parties of these winners all suffered net losses in the U.S. Senate, and none scored a gain of even 15 seats in the House. Since the rise of split-ticket voting after World War II, a successful presidential reelection has invariably turned into a "lonely landslide."

What would have to happen for George W. Bush to break this pattern and trigger a decisive Republican trend in the middle of a two-term presidency? Something similar to the phenomenon that enabled him to break all the rules and make gains in both the House and Senate in his first midterm: a continuation and acceleration of the significant breach between the Democratic party and the electorate that began to be obvious this fall.