Editor's note: Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" (Times Books) and the forthcoming book "Governing America" (Princeton University Press).
(CNN) -- Americans have been flooded with Republican presidential debates for several months. It seems that every week there is a new encounter between the GOP candidates.
This does not come as a surprise. For several decades, presidential campaigns have been starting earlier. Candidates seek to get a jump on the first caucuses and primaries in order to position themselves as the perceived front-runner and to be in position to win the large delegate counts on Super Tuesday. To do so, they have started to organize and fund-raise earlier and earlier. This year, we have witnessed another part of this phenomenon as the new multimedia world has created interest and space for multiple national debates.
There have been many reasons to be critical of the debates. If someone is trying to find substance, this is usually not the place to look. Candidates focus on providing the best sound bite and on trapping their opponents in embarrassing or controversial moments. With Donald Trump now scheduled to host a debate of his own, these spectacles can sometimes look more like a circus act than an opportunity to choose our next commander in chief.
Nonetheless, the pre-caucus debates have provided something useful to the Republican electorate and might very well offer a model that Democrats should use in the future as well. After all, the real purpose of these debates, and the many media interviews that surround them, is to determine not what a candidate would do once they were president but, rather, how a candidate will do on the campaign trail. Throughout these months, we have learned many of the strengths and weaknesses that these individuals exhibit in the campaign process before any voting has taken place.
When the vetting started in January, as the voting began and as the momentum of one victory starts to push candidates forward, the electorate could often make rash and uninformed decisions based on one performance or a short-term media frenzy that makes someone look like a winner. Scandals and flaws are often exposed in the middle of the primary season, once it's too late for the party to go back and look again at candidates who have fallen away.
The recent debate season has offered voters a longer look at the Republican field before they have made any choices. Several candidates who a few years ago might have gone rather far based on a dramatic caucus victory have fizzled.
Herman Cain fell to scandal after an initial rush of support. Michele Bachmann, Tim Pawlenty and Rick Perry, all of whom enjoyed early enthusiasm from their party, did not perform well in the national media spotlight -- a crucial test for anyone running for president -- nor did their campaigns offer enough juice to keep interest over time. While he has not fallen by the wayside, Rick Santorum has not created any major sparks during these debates, while Ron Paul, always colorful in his statements, has not been able to convince Republicans that he could win a broad coalition of support needed to defeat President Obama.
Former Massachusetts Gov. Mitt Romney has reminded voters of his well-known weaknesses. During the debates he has had trouble defending contrasting positions that fuel the argument he is a flip-flopper, a candidate who moves according to what will get him elected rather than what he believes in. He also has had trouble with the "likeability" factor, failing to charm voters and win their hearts rather than their minds.
At the same time, however, he has used the debates to display some notable strength as a campaigner. He has remained remarkably disciplined during most of these events, staying on message and keeping his cool, remaining a formidable presence and responding to his critics effectively.
While he has not spiked in the polls he has been able to protect his standing, which is notable compared with the other candidates' fluctuations. In a slow and steady approach, he has shown that he has more lasting power in the campaign process than some believed. He has also used these debates to define his candidacy around the economy and his business background, refusing thus far to get sucked into the culture wars.
Former Speaker of the House Newt Gingrich has also used the debate period to his favor. Although he has made some statements that have led to discussions about his ability to discipline himself, such as questioning the need for child labor laws, Gingrich has also been able to take on discussions about the big ideas defining his party and to take some stands, such as his defense of immigration, which allowed him to strengthen his claims of being the candidate who would build the broadest tent.
As a result of this early exposure to their menu of candidates, Republican voters will be in a stronger position when they go to the ballot box to make their choices. By January, the candidates will be relatively known quantities and many of the candidates with major vulnerabilities will be out of the running. Some of the air will also be taken out of the Democratic attacks down the road, since it will be hard to surprise voters by the fall of 2012.
To be sure, this period of ongoing debates is still an experiment, and it remains to be seen if the lessons influence the choices the voters make. Although having Donald Trump host a debate might seem absurd to many people, with viewers waiting to hear him tell candidates that they are fired, this extension of the national campaign season does have its uses to the parties. If Republicans take advantage of it, they might come away with a much better chance at taking back the White House.
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The opinions expressed in this commentary are solely those of Julian Zelizer.