The next presidential election is still 3 years away, and so-called "Bush fatigue" is giving the Democrats a premature sense of optimism about winning the White House in 2008.

But as Democrats ponder the successor to George Bush, they must recognize that an election at the conclusion of an unpopular president's second term does not necessarily assure a party turnover. An election featuring non-incumbents is a choice between the two candidates, not a referendum on the outgoing president's administration.

In fact, Al Gore would likely be president today if he had chosen to run in 2000 as Bill Clinton's protege and the perpetuator of the policies of the Clinton Administration. The economy was robust, the country was involved in no foreign entanglements, and Clinton had high approval ratings for his presidential policies - but low approval ratings for his personal activities, due to the plethora of ethical lapses. But Gore was never inclined to be Clinton's second banana, and instead he ran as an agent of change. Hence, the election was a choice between Gore and Bush.

Beset by the unresolved situation in Iraq, controversy over the Hurricane Katrina response, the spike in gasoline prices and early inflationary signals, polls indicate that the president's "approval" rating is just over 40 percent. By comparison, in the first year of their second terms, Clinton polled 61 percent approval and Ronald Reagan polled 57 percent.

Bush has no heir apparent. Vice President Dick Cheney is not running, nor is Governor Jeb Bush of Florida. The candidates in the 2008 Republican field have the flexibility to position themselves as distantly from the Bush Administration as expedience dictates. In fact, they could even adopt positions categorically opposed Bush policies, much like Vice President Hubert Humphrey in 1968 tried to run as the "peace" candidate even though he was part of the Johnson Administration and had supported the Vietnam buildup.

According to Washington insiders, the frontrunner for the 2008 Democratic nomination is New York Senator Hillary Rodham Clinton. All the other potential Democrats are trying to emerge as the "Stop Hillary" candidate. A recent USA Today/CNN poll put Clinton at 40 percent, with Massachusetts Senator John Kerry at 25 percent and former North Carolina senator John Edwards at 17 percent. The poll is encouraging to the anti-Clinton throng, since it indicates that 60 percent of Democrats do not now support Clinton, but it's also encouraging to the Clintonites, since they're only 10 percent shy of a majority.

Whether Clinton is the Democratic nominee heavily affects those in the Republican field and their respective strategies. For former New York mayor Rudy Giuliani and Arizona Senator John McCain, the two Republican frontrunners, stature is their forte. They argue that to beat "Team Clinton," the Republicans must field a candidate of heroic proportions. The other wannabes in the field have a different view: They're convinced that any Republican can beat Clinton, embracing the presumption that she is so polarizing and that she arouses such hostility that voters will reject her and vote for the Republican. If the election is a referendum on Hillary, they argue, she loses. Here's a sketch of possible Republican nominees:

Giuliani, age 61, was mayor of New York City for two terms (1993 to 2001), and he achieved legendary status for his crisis management of the September 11 World Trade Center terrorist strike. As mayor, Giuliani was tough on crime, and he pioneered the concept of flooding high-crime areas with police; he also is a fiscal conservative. On social issues, Giuliani supports abortion rights and gay rights. He has near universal name recognition. His appeal is pragmatic, not ideological. His theme is leadership, and his appeal is that he can win and can govern effectively.

 McCain, age 69, has been a senator for 19 years, and he was the author of a major campaign finance reform bill. He supports the Iraq War, and he has strong military credentials, in part because he was a prisoner of war in Vietnam. He is anti-abortion and an outspoken critic of congressional "pork," and he supports making generic drugs available. McCain is the true anti-Bush in the contest. Back in 2000 he beat Bush in the New Hampshire primary, and he lost the nomination because southern conservatives quickly rallied to Bush. McCain exudes maturity, and he has a reputation for quirky independence. If Republicans want a winner, he's it. His only drawback is age; he'd be 72 if he ran in 2008.

Bill Frist, age 53, is the Senate majority leader, and he has served as a senator from Tennessee for 12 years. He is retiring in 2006 to honor a term-limit pledge. Frist currently is fending off allegations that he profited from the sale of stock in a blind trust; and he didn't win any support from social issue conservatives when he supported stem cell research. Frist, a heart surgeon, has a great personal story, but he is generally viewed as bland and uninspiring. He's going nowhere.

George Allen, age 53, the Virginia senator and former governor, is quietly emerging as the anti-Hillary candidate. He is strongly opposed to abortion rights and gay rights, and he is convinced that he can "rally" the Republican base, particularly those who feel strongly about social issues. His strategy is issue-oriented, and he expects to build precinct organizations in the key primary states. Then, with Giuliani and McCain splitting the non-hard-core conservative vote, Allen will finish a close second, or even first. He would then emerge as the "Stop McCain" or "Stop Giuliani" candidate and argue that the party should nominate a "real Republican." Allen's prospects of winning are dim, but he will be a major player in 2008.

Chuck Hagel, age 59, is a two-term Nebraska senator and Vietnam veteran. He has been cautiously critical of the Iraq War, and he supports voluntary retirement accounts for social security. Like McCain, Hagel is thoughtful and independent-minded. He could emerge as the Republicans' 2008 "anti-war" candidate, and he would have great appeal in the Northeast.

Others mentioned include New York Governor George Pataki, Massachusetts Governor Mitt Romney, Arkansas Governor Mike Huckabee, Kansas Senator Sam Brownback and former House speaker Newt Gingrich.

But the GOP choice in 2008 is shaping up as the "Big Ones" (Giuliani, McCain) versus the "Rights Ones" (Allen, Frist), with Hagel as an intriguing dark horse. A poll last May gave Giuliani a 25-20 lead over McCain among Republican voters, with 10 percent for Jeb Bush and the remainder undecided. The early outlook: If either McCain or Giuliani wins the first three or four primaries, he'll sail to the nomination. Give an early edge to McCain.

As for the Democrats, the possibility that Clinton, age 58, won't run has engendered much ambitious posturing among second-tier candidates, including Indiana Senator Evan Bayh, Virginia Governor Mark Warner, New Mexico Governor Bill Richardson and retired general Wesley Clark. Those aspirants understand that they couldn't defeat Clinton in the primaries, but that in a Clinton-free field they could replicate Bill Clinton's feat in 1992 and win in a field of political midgets.

The most credible anti-Clinton contenders are Kerry, age 61, the Democrats' 2004 nominee, and Edwards, age 52, the 2004 vice-presidential nominee. Edwards likely will run to Clinton's left, using his "Two Americas" theme to appeal to minority voters, who comprise a disproportionately large segment of the Democratic primary electorate. Kerry could run on the premise that he is the real "anti-Bush" and that he deserves a second shot.

Another is Delaware Senator Joe Biden, age 63, who has considerable stature as a congressional insider, having served in the Senate for 33 years; he is the ranking minority member on the Foreign Relations committee. Biden is quietly lining up financial support throughout the country.

The emerging "anti-war" candidate is Wisconsin Senator Russ Feingold, who already is visiting New Hampshire. He has called for a withdrawal timetable for U.S. troops in Iraq.

The early outlook: It is hard to imagine Clinton not running, and she will have plenty of competition. Edwards and Feingold will struggle for support from hard-core liberals, and Warner, a social-issue liberal, will run as a fiscal conservative. Much depends on the issue mix. If the war is over and the economy is booming, the Democrats will be inclined to back a winner, namely, Clinton. If the war is still unresolved, Feingold will be formidable. If the economy is sour, Edwards' soak-the-rich populism will have appeal.

In short, the more problems besetting the country, the greater the likelihood that Clinton will lose - and the greater the likelihood that Giuliani or McCain will win. Conversely, a rebound in the president's popularity will aid both Allen and Clinton.