Candidates to replace George W. Bush were naturally bandied about by pundits the moment he was re-elected in 2004; however, most aspirants didn't formally announce their intentions to run until a few months ago. Some still haven't committed.

Hats in the ring or not, oddsmakers have made lines for all the contenders, plus a few pretenders.

Here's a rundown:

Hilary Clinton - The Comeback Kid

Whatever your political affiliation, you have to admire her ability to bounce back. In 1998, she was the most publicly cheated on woman in the world. As a United States senator, she voted to approve the country's role in the Iraq war. Now, Hilary Clinton is the 2/1 favorite to become the next president, and she's doing it hand-in-hand with her husband and by promising to end the war.

"I'm in. And I'm in to win," was the announcement on her website January 20. Since then, she's been burning up the polls, consistently emerging as the top choice within the Democratic Party as well as versus various Republican candidates.

According to oddsmakers, Clinton's biggest rival within her own party is the junior senator from Illinois, Barack Obama. Clinton is is at 5/9 odds to win the Democratic nomination; Obama is getting 2/1.

Despite the fact many believe the 45-year-old Obama isn't qualified to become president, he does hold one strategic advantage over Clinton: he opposed the Iraq war from the start.

"Being a leader means that you'd better do what's right and leave the politics aside because there are no do-overs on an issue as important as war," Obama said in a speech Tuesday.

Expect Clinton's initial support of the Iraq war to be a major point of debate in the coming months. Depending on how she handles the heat, the odds could very well change in Obama's favor.

And on the Right...

The Republicans have their work cut out in 2008 and owe most of their problems to President Bush. In a Newsweek poll taken in June, Bush's approval rating came in at 26 percent, the lowest of any sitting president since Richard Nixon in January 1974. As a result, the Republican Party is getting 7/5 odds to win the election versus the favored Democrats at 1/2.

Two frontrunners have emerged to snag the GOP nomination: former Mayor of New York City Rudy Giuliani and former Tennessee Senator and Law & Order actor Fred Thompson. Giuliani is at 3/2 odds to be named the Republican candidate; Thompson is at 2/1.

The close odds seem to defy a CBS News poll taken June 26-28 that gave Giuliani a significant lead over Thompson, 34 percent to 21.

Many Americans fondly remember Giuliani's leadership during the attacks of September 11, 2001 and point to his success reducing crime in New York City.

But while his tough stances on terrorism and government spending sit well with many Republicans, his three marriages, pro-choice position and support for gay civil unions certainly won't help his cause with Christian conservatives.

As for Thompson, he's looking a lot like a horse that's about to open it up down the stretch. Though he hasn't formally announced his candidacy for president, he's expected to do so soon. What's more, it's expected he'll have a nice little war chest from which to work.

As one washingtonpost.com blogger wrote, Thompson "has one major factor working in his favor: His political base is in Tennessee -- a state whose Republican donors have shown time and time again their willingness to dig deep to support candidates."

The Dark Horse

It's been a long time since former Vice President Al Gore blew the 2000 presidential election with a healthy dose of boring speeches and bad decisions, most notably distancing himself from the personal scandals of Bill Clinton, despite the president's solid approval rating and exceptional campaigning abilities.

Gore has said he's "not planning to be a candidate again," but hasn't ruled it out entirely.

Book managers are showing caution with Gore, who's getting 13/1 odds to become president and would become an instant contender should he decide to run.

Remember that Gore actually won the popular vote in the 2000 election and has remained very much in the public eye since then, starring in the Academy Award-winning documentary An Inconvenient Truth and co-founding the Live Earth series of concerts, which were held July 7.

One has to think, for Gore, it'll be tough to decline a shot at redemption.