If the Tennessee twosome of Al Gore and Fred Thompson keep the political world guessing much longer about their presidential ambitions, they might find themselves crowned as front-runners.

That is an exaggeration of course, but as the former Democratic vice president and one-time Republican U.S. senator turned actor keep considering their White House options, their poll numbers keep rising.

Whether this reflects true love from the voters or the normal human emotion of wanting more choices won't be clear until when and if either man gets into the race.

But the potential of either to shape the races for the Democratic and Republican presidential nominations is clear.

Gore narrowly lost the presidency to George W. Bush in 2000 and has not closed the door on running this time. He trails Sen. Hillary Clinton in polls of Democratic voters. Yet just by keeping in the news with his campaign against global warming, Gore is giving Sen. Barack Obama and former Sen. John Edwards a run for their money for second place.

Most striking is a round of recent polls in key states that show Gore might be the party's strongest candidate in November against the Republicans.

Thompson served eight years in the Senate after taking a hiatus from a television and movie career to which he returned. (He is Arthur Branch on NBC's Law and Order, and a host of movie roles in which he generally plays strong, decisive military and political leaders.) In recent months, Thompson has been sending signals he might well run, but has not committed.

Even so, he runs third in many polls of Republican voters behind former New York Mayor Rudy Giuliani and Sen. John McCain of Arizona, and shows surprising strength in general election match-ups against the Democrats in battleground states.

How either Gore or Thompson would fare if they actually went for the brass ring would depend heavily on how quickly they could make the change from public figure to candidate.

The other candidates have a significant head start in recruiting campaign staff and major supporters in key states, not to mention fund-raising. Most of the major candidates have already raised $20 million or more and the first face-off in the nomination contests is eight months away in Iowa.

Yet the front-runners would be foolish to dismiss either man as just the flavor of the month.

Gore, especially, has a network of supporters from his previous runs for national office. He has become a celebrity for his work on climate change and he won an Academy Award for his film, An Inconvenient Truth.

In Quinnipiac University polls of voters in Florida, Ohio and Pennsylvania, the three most critical "swing states" in a presidential election, that were released last week, Gore ran better than Sens. Clinton or Obama in trial match-ups with the Republican leaders. Given the hunger within the Democratic Party to win the White House next year, those numbers are likely to increase the pressure on Gore to run.

Perhaps most striking was that the share of voters in national polls who said they had an unfavorable opinion of Gore has generally been declining in recent months, perhaps because he has not been subjected to the back-and-forth negativity that comes with campaigning.

Thompson, who ran second to Giuliani in a recent Los Angeles Times/Bloomberg poll of Republicans nationally, remains unknown to two-thirds of voters; although the assumption is that his face recognition would be much, much higher and probably add to his popularity.

Yet in the Quinnipiac polls of Pennsylvania, Ohio and Florida, he ran much better against Sens. Obama and Clinton than had former Massachusetts Gov. Mitt Romney in recent surveys. Romney has been the leading fund-raiser and trying to become the darling of party conservatives, the niche that Thompson would seek if he enters the race.

Moreover, although not nearly as well known as the other major Republican aspirants, Thompson's favorable-to-unfavorable ratio was similar to that of front-runner Giuliani and much better than the other candidates.

Of course polls can change like the wind, but both men are showing they will need to be reckoned with if they decide to run.