The GOP has traditionally been the party of political primogeniture. From Ronald Reagan to George Herbert Walker Bush to Bob Dole to George W. Bush, Republicans have nominated the man who could best lay claim to being the natural heir, either by virtue of his service to the party or his ability to ring up early endorsements and financial backing from the party faithful. In George W. Bush's case, he literally was the eldest son of the last Republican president and inherited much of the support his father had amassed over decades.

But 2008 is different. There is no clearly anointed candidate in the field. The one who looked like he might best fill the role, Sen. John McCain, has been too much of a party dissident on bedrock Republican issues like tax cuts to easily become the party favorite. Although he still might pull off a victory in the early primaries, it's far from certain at this point.

And the other major candidates are even less in the mold of a natural successor. Former Sen. Fred Thompson has little claim to the mantle. An eight-year senator and former Republican congressional staffer, he did little in office, and even less since leaving Washington, to earn the right to be the party's standard-bearer. But he's also a movie star with folksy appeal, whose on-camera persona exudes conservatism.

Mitt Romney, winner of the first Republican straw poll in Iowa this week, captured the governorship of Massachusetts, the most liberal state in the union, largely by running away from traditional Republican issues. His recent conversion to social conservative may be genuine, but many Republicans would like to see Romney's conservative credentials seasoned a bit more. Still, he's articulate and good-looking, with plenty of money -- his own and what he's been able to raise -- to run a tough race.

Then there's Rudy Giuliani, in some ways the most enigmatic of the major Republican candidates. On the one hand, he's been fighting for some traditional Republican values for a long time. As a U.S. attorney appointed by President Ronald Reagan, he established his tough law-and-order image early in his career by taking on organized crime and political corruption, and then burnished his crime-fighting aura as mayor of New York, driving down the crime rate in the city by an astonishing 56 percent and homicides by 66 percent.

But he's also snubbed fellow Republicans. In 1994, Giuliani endorsed Democrat Mario Cuomo for re-election as New York governor over Republican State Senator George Pataki, who ended up winning the close election.

Giuliani also spans the ideological spectrum on other issues. He's a hawk on defense and foreign policy; moreover, one with chutzpah. He once had Palestine Liberation Organization Chairman Yasser Arafat ejected from a Lincoln Center gathering to celebrate the 50th anniversary of the United Nations, which earned him a reprimand from the Clinton administration but plaudits from Republicans who considered Arafat a terrorist and corrupt thug. But on social issues, Giuliani is clearly the most liberal of the Republican pack.

The lack of a natural successor among the candidates will challenge Republican primary voters' traditional fallback position when they go to the polls next year. They won't necessarily pick the candidate they are most familiar with or the one who seems to have paid the most dues. Republicans may actually be forced to choose the candidate they think would be most likely to win against the Democrat nominee, which looks increasingly likely to be Hillary Clinton.

All of this makes the Republican race more interesting than the Democratic contest. Hillary Clinton's early lead in both fundraising and opinion polls makes her anointing seem almost inevitable, despite the media's continued fascination with Barack Obama. Few people, including the pundits, however, are confident they know how the Republican race will turn out.

Some might argue that it doesn't much matter whom the Republicans pick; 2008 is destined to be a Democratic year. Maybe. But the lack of an heir-apparent nominee just might become an advantage next November if Republicans pick someone with broader appeal than the usual, safe GOP niche.