Eight years ago, Republicans scored their biggest off-year election victories in decades, capturing both houses of Congress and most big-state governorships.

In politics as in life, however, what goes around comes around. And so this year, the GOP is battling to keep its majorities in the House and the nation’s governorships and to regain the Senate.

President Bush’s popularity undoubtedly will help. But all signs indicate the congressional races may remain in doubt for many months. A plausible case can be made for either party to win both houses, maintain the current split or even swap their present House and Senate majorities.

What seems in danger is the current Republican majority of governorships, which includes seven of the eight largest states. Democrats hope to gain at least an even split, while picking up a number of smaller states.

In part, this represents the normal ebb and flow of politics. Three veteran GOP governors Wisconsin’s Tommy Thompson, Pennsylvania’s Tom Ridge and Massachusetts’ Paul Cellucci have joined the administration. Nine other Republicans, some term-limited, are not running for re-election.

By contrast, only six Democratic incumbents are not running again.

Of the biggest states, Republicans are favored where incumbent Govs. Rick Perry of Texas, Jeb Bush of Florida, George Pataki of New York and Bob Taft Jr. of Ohio lead the GOP state ticket.

Democratic Gov. Gray Davis of California, hurt by low job approval but helped by a conservative Republican rival, is a shaky re-election favorite. And Democrats hope to regain governors’ chairs in three states that voted Democratic in the last three presidential elections and where Republican incumbents are not running.

In Illinois, where unpopular one-term Republican George Ryan is stepping down, GOP state Atty. Gen. Jim Ryan, no relation, is being challenged by a Democratic congressman from Chicago, Rod Blagojevich. Illinois last elected a Democratic governor 30 years ago.

In Michigan, three Democrats and two Republicans are running to succeed three-term Republican Gov. John Engler. Polls give the Democrats an edge.

And in Pennsylvania, the winner of next week’s bitter Democratic primary battle between former Philadelphia Mayor Ed Rendell and Auditor General Bob Casey Jr., son of the last Democratic governor, will be favored in a state where the governorship has rotated between the parties every eight years for a generation.

Both parties have long regarded control of statehouses as a way to influence politics within the state as well as to help win presidential contests. Governors played a major role in helping to elect both Bush and former President Bill Clinton.

Perhaps the most important national effect is that statehouses have become far more of a presidential breeding ground than the Senate.

Four of the last five presidents were governors. The last senator elected president was John F. Kennedy.

The GOP triumphs of 1994 produced one presidential candidate, George W. Bush, and two potential national candidates in Ridge and Pataki. And 1998 produced another potential candidate in Jeb Bush.

So far, governors haven’t played much of a role in the early Democratic maneuvering for 2004. The main governors who have been mentioned are such little-known figures as Vermont’s Howard Dean, who may well run; Georgia’s Roy Barnes, a distinct long shot; and California’s Davis, who has his own problems at home.

But beyond that, some current or future Democratic governors such as Iowa’s Tom Vilsack, Maryland’s Kathleen Kennedy Townsend and New Mexico’s Bill Richardson could wind up on a future national ticket.

Carl Leubsdorf is Washington bureau chief of the Dallas Morning News.