Republicans in their search for the best candidate for president in 2008 are going through what Democrats have gone through in the past. The legacy of great leaders, for Democrats Franklin Roosevelt, for Republicans Ronald Reagan, casts a long shadow for years afterwards. But life is full of surprises.

Who would have guessed that Roosevelt's successor, Harry S Truman, would lay the groundwork for American security with the Marshall Plan, the North Atlantic Treaty Organization and the containment of Soviet expansionism? Who would have predicted that Reagan would be followed by two men named George Bush would first contain and then destroy the regime of Saddam Hussein in Iraq?

As Republicans look over the field of Mitt Romney, former governor of Massachusetts; Rudy Giuliani, former mayor of New York City; John McCain, Senator from Arizona; and Fred Thompson, former senator from Tennessee, they don't see Reagan and some are disappointed. But no one knows how these men will perform if elected president. As the Greek philosopher Aristotle wrote, "Power will show a man."

The four leading GOP hopefuls have pluses and minuses. Romney was governor of a major (and liberal) state, with genuine experience in making executive decisions. Also, he turned around several failing businesses and, most notably, salvaged the scandal-plagued 2002 Winter Olympics in Salt Lake City.

On the other hand, Romney's policy positions have changed, albeit in a conservative direction. When he challenged Sen. Edward Kennedy in 1994, Romney did not oppose abortion on demand or gay rights legislation (liberal southern senators never challenged segregation laws either). He opposes both now.

Romney has the distinction of being married to the same woman for many years, not surprising given his Mormon faith. Still, some Evangelicals and Roman Catholics are troubled by that faith's unique theology, while many liberals are troubled even more by his strong family orientation.

By contrast, Rudy Giuliani, who won acclaim for his actions following the enemy attack on 9/11, has been married three times and is neither pro-life nor an opponent of gay rights laws. He intends to prosecute the war on terrorists, and, like Romney, strongly supports tax relief to keep the economy growing.

Giuliani has not recanted any of his positions, which conflict with the pro-life and pro-marriage Republican platform. But he stresses his personal opposition to abortions, claims that he reduced their incidence as mayor, and encourages adoption as an alternative.

The abortion question hinges on the same Supreme Court that gave us the "abortion on demand" decisions in Roe v. Wade (1973) and Planned Parenthood v. Casey (1992) that are treated as the supreme law of the land. Giuliani, like other Republican hopefuls, has promised to appoint "strict construction" justices to our highest court. But he has also said that such a posture does not imply overturning the abortion decisions.

John McCain, twice married, has established a national reputation as a maverick. In Republicans' eyes, he has been obsequious to the liberal media, despite a conservative voting record in the Senate. A prisoner of war in Vietnam for seven years, he is entitled to immense respect and appreciation.

Still, just as it has been said of Romney, that we are electing a president, not a pastor; so it may be said of McCain, that we are electing a president, not a war hero. McCain's lack of enthusiasm for tax cuts to encourage economic growth, his support for a liberal immigration policy and periodic independence, such as joining the "gang of 14" that held up President Bush's judicial appointments, have not pleased many GOP voters.

McCain is also coauthor with liberal Democrat Russ Feingold of campaign spending reform legislation, which has so far passed constitutional muster in federal courts. But I will not hesitate to call it unconstitutional for its limits on free speech and press under the guise of regulating contributions to political candidates.

Finally, Fred Thompson, also twice-married, well known from his role on TV's "Law and Order," supported McCain-Feingold, despite a conservative Senate voting record. He was counsel for the minority in Watergate days, and has provided legal help to political causes both right and left. His delayed entry into the presidential race was made possible by his TV celebrity, and enabled him to ride out the early skirmishing in GOP ranks.

Thompson's claim to fame is his supposed "gravitas," that elusive quality that somehow indicates that a man has what it takes to be President. Some, including me, have seen what looks more like ambivalence or indifference. It's good to look like the office is seeking you rather than the reverse, but one must nevertheless have what the late Hubert Humphrey called "fire in the belly."

In our hurried political calendar for 2008, the primaries will largely be over by March, a full four months before the nominating conventions begin. One only hopes that we are neither tired of the process by then nor regret who emerges victorious from those early contests. Time, literally, will tell whether a good choice has been made.

ABOUT THE WRITER Richard Reeb taught political science, philosophy and journalism at Barstow College from 1970 to 2003. He is the author of "Taking Journalism Seriously: `Objectivity' as a Partisan Cause" (University Press of America, 1999). He can be contacted at rhreeb@verizon.net.