For most of this presidential cycle, the suggestion that Republicans needed more debates would have been met with laughter, derision, anger, or a combination of all three. At times, the candidates met more than once in a week for formal or informal debates, most of which have now mainly disappeared from memory, save for a few embarrassing gaffes or brief moments of glory. From September 2011 to the week before the Arizona and Michigan primaries last month, the candidates never went more than three weeks without a formal debate, save for the Christmas holidays.

That is, until now. The last debate was in Arizona four weeks ago Wednesday, and at least one of the Republican candidates wants to put another on the schedule. On Sunday, Rick Santorum challenged Mitt Romney to a one-on-one debate during his appearance on ABC's This Week. Calling Romney a "weak candidate," Santorum said Romney was "hiding" behind billionaires on the campaign trail and needed to be called to account. "I'd love to be able to get one-on-one with Gov. Romney," Santorum told the ABC audience, "and expose the record that would be the weakest record we could possibly put up against Barack Obama."

Romney may need a game-changer — not to win the nomination, but to win it more quickly.

Those who watched the previous debate, in Arizona, might be somewhat surprised by that challenge. Santorum came off the worse after Romney spent all night attacking him, falling into a debate trap of explaining too often and attacking too little. Of course, Newt Gingrich and Ron Paul also took turns hammering Santorum, allowing Romney to mostly escape attacks and reassume a commanding presence in the race.

Santorum might feel that the potential reward of another debate would be worth risking another mediocre showing. Santorum has won two primaries and a caucus since the last debate, and he has a fair shot at winning Louisiana's primaries on Saturday, while Tuesday's primary in Illinois looks likely to break for Romney. Starting in April, though, the primary schedule looks a lot less friendly for the Pennsylvanian. There will be eight primaries — three on April 3, and five more on the 21st — and Santorum probably only has a significant chance of winning in Wisconsin and Pennsylvania. If he can gain traction and catch up in the delegate hunt, May looks more promising, with seven of the eight states in the South or Midwest. But by the time Santorum gets there, his strength may have faded if he can't keep up with Romney in April. Santorum has managed to outmaneuver Gingrich to become Romney's most significant competitor, but without real wins to close the delegate gap, his credibility will evaporate. He needs a game-changer.

Would Romney agree to a debate? Conventional wisdom would dictate that a frontrunner avoid getting tangled in another debate. However, Romney may also need a game-changer — not to win the nomination, but to win it more quickly. Thanks to rule changes made by the RNC after John McCain won the nomination before most of the country got a chance to vote, Romney has to outlast everyone else and hope that he gets enough delegates to clinch a convention majority. While his opponents continue to campaign, the delegate splits at least give the impression that Romney won't be able to close the deal, leaving the possibility open for a contested convention. A big debate win for Romney, or even just another defensive and distracted performance from Santorum, might be enough to derail Santorum and produce the tipping point that Romney needs to get voters to climb onto his bandwagon.

Of course, Newt Gingrich and Ron Paul might object to getting shut out of a debate, and not unreasonably. Gingrich has won two states, and both have delegates in their column. However, Paul's campaigning has slowed in recent days, and Gingrich might soon run out of cash. If Gingrich can't win in Louisiana, he won't be much of a factor in the April contests anyway, and perhaps not even in the rest of the Southern states in May. Paul hasn't won any contests yet, and has become all but irrelevant.

The most important question is whether the voters need another debate — and perhaps the answer is yes, given the right conditions. None of the previous debates used a format that produced real insight into policy or governing temperament, owing mainly to the number of candidates on stage and the media's insistence on using game-show techniques. With only the two frontrunning candidates on stage, the time pressure on answers created by the need to get to seven, eight, or nine candidates evaporates. Romney and Santorum would have more time for substantive answers to substantive questions — presuming the moderator focused on issues that matter most to voters, and not silly questions about underwear and personal squabbles. In a revamped format that perhaps could take its cues from the Gingrich-Herman Cain debate, one last face-off might produce significant value for voters still choosing which candidate to support.

After Louisiana, we have 10 days until the next primaries, on April 3. That seems like a custom-made opening for a new event. If the media and the two candidates take it seriously, it could provide an excellent springboard into the second half of the nomination schedule.